In his somber moments, John Newton (1725-1807), Anglican cleric, argues that humans are monsters, fools, worse than beasts and worse than the meanest idiots, and resemble the devil.

Newton (1725-1807), contemporary portrait

On Man in his Fallen Estate.

Lord, what is Man!

Dear Sir,

We hear much in the present day of the dignity of human nature. And it is allowed that man was an excellent creature as he came out of the hands of God; but if we consider this question with a view to fallen man, as depraved by sin, how can we but join with the Psalmist in wonder that the great God should make any account of him? 

Man is a monster, a vile, base, stupid, obstinate, and mischievous creature

The Head of Medusa by Peter Paul Rubens, circa 1618.

Fallen as man is from his original state of happiness and holiness, his natural faculties and abilities afford sufficient evidence that the hand which made him is Divine. He is capable of great things. His understanding, will, affections, imagination, and memory—are noble and amazing powers. But view him in a moral light, as an intelligent being, incessantly dependent upon God, accountable to him, and appointed by him to a state of existence in an unchangeable world: considered in this relation—man is a monster, a vile, base, stupid, obstinate, and mischievous creature; no words can fully describe him. Man, with all his boasted understanding and attainments, is a fool: so long as he is destitute of the saving grace of God, his conduct, as to his most important concerns, is more absurd and inconsistent than that of the most contemptible idiot; with respect to his affections and pursuits, he is degraded far below the beasts; and for the malignity and wickedness of his will, can be compared to nothing so properly as to the devil. 

The heart itself is universally deceitful, and desperately wicked

Nero's Torches (Christian Candlesticks), Henryk Siemiradzki (1843–1902)  

The question here is not concerning this or that man, a Nero or a Heliogabalus, but concerning human nature, the whole race of mankind, the few excepted who are born of God. There is indeed a difference among men, but it is owing to the restraints of Divine Providence, without which earth would be the very image of hell. A wolf or a lion, while chained, cannot do so much mischief as if they were loose, but the nature is the same in the whole species. Education and personal interest, fear and shame, human laws, and the secret power of God over the mind, combine to form many characters that are extremely decent and respectable; and even the most abandoned are under a restraint which prevents them from manifesting a thousandth part of the wickedness which is in their hearts. But the heart itself is universally deceitful, and desperately wicked.

Man is a fool

"Keying Up" - The Court Jester, William Merritt Chase (1849–1916)  

Man is a fool. "Professing themselves to be wise, they became fools." Romans 1:22. He can indeed measure the earth, and almost count the stars; he abounds in arts and inventions, in science and policy—and shall he then be called a fool? The ancient Heathens, the inhabitants of Egypt, Greece, and Rome, were eminent for this kind of wisdom. They are to this day studied as models by those who aim to excel in history, poetry, painting, architecture, and other exertions of human genius, which are suited to polish the manners without improving the heart. But their most admired philosophers, legislators, logicians, orators, and artists, were as destitute as infants or idiots of that knowledge which alone deserves the name of true wisdom. Professing themselves to be wise, they became fools. Ignorant and regardless of God, yet conscious of their weakness, and of their dependence upon a Power above their own, and stimulated by an inward principle of fear, of which they knew neither the origin nor right application, they worshipped the creature instead of the Creator, yes, placed their trust in stocks and stones, in the works of men's hands, in non-entities and chimeras. An acquaintance with their mythology, or system of religious fables, passes with us for a considerable branch of learning, because it is drawn from ancient books written in languages not known to the vulgar; but in point of certainty or truth, we might receive as much satisfaction from a collection of dreams, or from the ravings of lunatics. If, therefore, we admit these admired sages as a tolerable specimen of mankind, must we not confess that man, in his best estate, while uninstructed by the Spirit of God, is a fool? But are we wiser than they? Not in the least, until the grace of God makes us so. Our superior advantages only show our folly in a more striking light. Why do we account any people foolish? A fool has no sound judgment; he is governed wholly by appearances, and would prefer a fine coat to the deed to a large estate. He pays no regard to consequences: fools have sometimes hurt or killed their best friends, and thought they did no harm. A fool cannot reason, therefore arguments are lost upon him. At one time, if tied with a straw, he dares not stir; at another time, perhaps, he can hardly be persuaded to move, though the house were on fire. Are these the characteristics of a fool? Then there is no fool like the sinner, who prefers the toys of earth to the happiness of heaven; who is held in bondage by the foolish customs of the world; and is more afraid of the breath of man, than of the wrath of God. 

Man is a beast and worse than a beast

Beast (Henry Philip "Hank" McCoy) is a fictional superhero appearing in American comic books published by Marvel Comics and is a founding member of the X-Men

Again, Man in his natural state is a beast, yes, below the beasts which perish. In two things he strongly resembles them; in looking no higher than to sensual gratifications, and in that selfishness of spirit which prompts him to propose himself and his own interest as his proper and highest end. But in many respects he sinks sadly beneath them. Unnatural lusts, and the lack of natural affection towards their offspring, are abominations not to be found among the brute creation. What shall we say of mothers destroying their children with their own hands, or of the horrid act of self-murder! Men are worse than beasts likewise in their obstinacy; they will not be warned. If a beast escapes from a trap, he will be cautious how he goes near it again, and in vain is the net spread in the sight of any bird. But man, though he be often reproved, hardens his neck; he rushes upon his ruin with his eyes open, and can defy God to his face, and dare damnation. 

Man resembles the devil

William Blake's illustration of Lucifer as presented in John Milton's Paradise Lost.

Once more, Let us observe how man resembles the devil. There are spiritual sins, and from these in their height the Scripture teaches us to judge of Satan's character. Every feature in this description is strong in man; so that what our Lord said to the Jews is of general application, "You are of your father the devil, and the lusts of your father you will do." Man resembles Satan in pride: this stupid, wicked creature values himself upon his wisdom, power, and virtue, and will talk of being saved by his good works; though if he can, Satan himself need not despair. He resembles him in malice; and this diabolical disposition often proceeds to murder, and would daily, if the Lord did not restrain it. He derives from Satan the hateful spirit of envy: he is often tormented beyond expression, by beholding the prosperity of his neighbors; and proportionably pleased with their calamities, though he gains no other advantage from them than the gratification of this rancorous principle. He bears the image likewise of Satan in his cruelty. This evil is bound up in the heart even of a child. A disposition to take pleasure in giving pain to others, appears very early. Children, if left to themselves, soon feel a gratification in torturing insects and animals. What misery does the wanton cruelty of men inflict upon cocks, dogs, bulls, bears, and other creatures, which they seem to think were formed for no other end than to feast their savage spirits with their torments! If we form our judgment of men, when they seem most pleased, and have neither anger nor resentment to plead in their excuse, it is too evident, even from the nature of their amusements, whose they are and whom they serve. And they are the worst of enemies to each other. Think of the horrors of war, the rage of duelists, of the murders and assassinations with which the world is filled, and then say, "Lord, what is man!" Further, if deceit and treachery belong to Satan's character, then surely man resembles him. Is not the universal observation, and complaint of all ages, an affecting comment upon the Prophet's words, "Trust not in a friend, put no confidence in a guide, keep the doors of your mouth from her that lies in your bosom, for they hunt every man his brother with a net?" How many have at this moment cause to say, with David, "The words of his mouth were smoother than butter, but war was in his heart; his words were softer than oil, yet were they drawn swords!" Again: Like Satan, men are eager in tempting others to sin; not content to damn themselves, they employ all their arts and influence to draw as many as they can with them into the same destruction. Lastly: In direct opposition to God and goodness, in contemptuous enmity to the Gospel of his grace, and a bitter persecuting spirit against those who profess it, Satan himself can hardly exceed them. Herein, indeed, they are his agents and willing servants; and because the blessed God is himself out of their reach, they labor to show their despite to him in the people of his people. 

"Lord, what is man!"

Leonardo da Vinci's Vitruvian Man displays the proportions of a man.

I have drawn but a sketch, a few outlines, of the picture of fallen man. To give an exact copy of him, to charge every feature with its full aggravation of horror, and to paint him as he is—would be impossible. Enough has been observed to illustrate the propriety of the exclamation, "Lord, what is man!" Perhaps some of my readers may attempt to deny or extenuate the charge, and may plead, that I have not been describing mankind, but some of the most abandoned of the species, who hardly deserve the name of men. But I have already provided against this exception. It is human nature I describe; and the vilest and most profligate individuals cannot sin beyond the powers and limits of that nature which they possess in common with the more mild and moderate. Though there may be a difference in the fruitfulness of trees, yet the production of one apple decides the nature of the tree upon which it grew, as certainly as if it had produced a thousand: so in the present case, should it be allowed that these enormities cannot be found in all people, it would be a sufficient confirmation of what I have advanced, if they can be found in any; unless it could be likewise proved, that those who appeared more wicked than others, were of a different species from the rest. But I need not make this concession; they must be insensible indeed who do not feel something within them so very contrary to our common notions of goodness, as would perhaps make them rather submit to be banished from human society, than to be compelled to disclose to their fellow-creatures every thought and desire which arises in their hearts. 

Man is capable of the most atrocious crimes

The spiked heads of executed criminals once adorned the gatehouse of the medieval London Bridge.

Many useful reflections may be drawn from this unpleasant subject. We cannot at present conceive how much we owe to the guardian care of Divine Providence, that any of us are preserved in peace and safety for a single day in such a world as this. Live where we will, we have those near us, who, both by nature, and by the power which Satan has over them, are capable of the most atrocious crimes. But He whom they know not, restrains them, so that they cannot do the things that they would. When he suspends the restraint, they act immediately; then we hear of murders, rapes, and outrages. But did not the Lord reign with a strong hand, such evils would be perpetrated every hour, and no one would be safe in the house or in the field. God's ordinance of civil government is one great means of preserving the peace of society; but this is in many cases inadequate. The heart of man, when fully bent upon evil, will not be intimidated or stopped by gibbets and racks. 

Can beasts and devils inherit the kingdom of God?

The Adoration of the Golden Calf by Nicolas Poussin

How wonderful is the love of God in giving his Son to die for such wretches! And how strong and absolute is the necessity of a new birth, if we would be happy! Can beasts and devils inherit the kingdom of God? The due consideration of this subject is likewise needful, to preserve believers in an humble, thankful, watchful frame of spirit. Such we once were, and such, with respect to the natural principle remaining in us, which the Apostle calls the flesh, or the old man, we still are! The propensities of fallen nature are not eradicated in the children of God, though by grace they are made partakers of a new principle, which enables them, in the Lord's strength, to resist and mortify the body of sin, so that it cannot reign in them. Yet they are liable to sad surprisals; and the histories of Aaron, David, Solomon, and Peter, are left on record, to teach us what evil is latent in the hearts of the best men, and what they are capable of doing if left but a little to themselves. "Lord, what is man!"

Source: Newton, John.  The Works of the Rev. John Newton.  Volume I, London: J. Johnson, St. Paul's Church-yard and J. Smith, No 6, Coleman-Street-Buildings, 1808, Letter XXXIII, pages 332-339.