Why did early Christians worship Jesus as God even though He was crucified? Was it creativity and inventiveness?

THE CREATIVITY OF THE EARLY CHURCH

Jesus depicted with the alpha and omega letters in the catacombs of Rome from the 4th century

The belief that Jesus is God was not idolatry or polytheism

Jesus and his twelve apostles, fresco with the Chi-Rho symbol ☧, Catacombs of Domitilla, Rome.

It has to be said, too, that Bultmann's reliance on the creativity and inventiveness of the early church places a serious strain on our credulity.  It ignores, for example, the powerful disincentives to divining Jesus which operated in the cultural milieu in which the gospels were born.  The early believers were Jews and the apostles were Jews, and nothing was more basic to their ideology than a horror of idolatry and polytheism.  For James suddenly to decide to worship his brother or Saul of Tarsus to pray to a crucified Messianic pretender of John the place another beside God as his equal borders on the inexplicable.  Some overwhelming force of evidence or some irresistible spiritual power might sweep such men along to such a faith, but they certainly had no predisposition to it.  On the contrary their every instinct protested against it.  As Hoskyns and Davey point out, "The gospel was as much a scandal to the first century as it is to the twentieth."

It surely required the impulse of more than ordinary human loyalty to divinize a man crucified for blasphemy and Messianic delusions

Icon of The Ladder of Divine Ascent (the steps toward theosis as described by St. John Climacus) showing monks ascending (and falling from) the ladder to Jesus, Saint Catherine's Monastery.

To ascribe the gospel portrait of Jesus to the inventiveness of the early church also ignores the horrendous disadvantages under which Jesus laboured as a candidate for deification.  Suppose that the monotheist prejudices of first-century Jews had been overcome and that they were open to some extension of their notion of deity; suppose they were even willing to entertain the idea that a man might, in some sense, be God; would they have turned into a crucified man, one whose weakness was only too palpable and whose sinful, criminal status had been highlighted so dramatically?  It surely required the impulse of more than ordinary human loyalty to divinize a man crucified for blasphemy and Messianic delusions.  Even in a Hellenistic milieu such a movement would have been totally unlikely, as Martin Hengel points out: "The incarnation of a divine figure and still more his shameful death on the cross was not a 'point of contact' but a 'scandal' and a 'stumbling block'."  Men like Pliny regarded the worship of Jesus as "depraved folly" and "for educated or noble men of antiquity the crucified Jesus as only an expression of folly, shame and hatefulness".  Logically, then, increased contact with Greek thought should have mean either a playing down of Jesus' divinity or a rapid descent into Docetism.  Whatever the dynamics of the development of early Christian doctrine it certainly cannot be explained as an attempt to conciliate its intellectual environment.  Instead, the Pauline gospel recklessly insisted on two blatantly incompatible truths: the lordship of Jesus and the primacy of the cross.

What can explain the emergence of the church?

An Eastern icon depicting the Descent of the Holy Spirit. The date of Pentecost is considered the "Birthday of the Church".

There remains the fact that any attempt to explain 'the Christ of faith' as a creation of the early church still leaves the question, how do we account for the early church?  What can explain the emergence in first-century Palestine of a rapidly expanding community of men and women who preached his divinity with astonishing fervour and stood ready to lay down their lives for the belief that he was Lord of creation?  The Christ of the New Testament tradition could account for such a phenomenon.  He saw himself as the Son of God, spoke like the Son of God and acted like the Son of God.  In vindication of his deity, he was raised from the dead.  In accordance with his promise and in pursuance of his ministry he poured out the Holy Spirit.  Such a Christ explains the other facts such as the faith of the church and the expansion of Christianity.  He also accounts for the New Testament itself.  Indeed, if the Jesus of history was not the Christ of faith, the very existence of the New Testament becomes virtually inexplicable.  Is the Christ of the Epistle of James the work of the apostle's imagination?  Is the Jesus of the synoptics the product of a syndicate?  Is the Logos of John an invention of genius?  And who was Peter kidding when he wrote, "Though you have not seen him, you love him" (1 Pet 1:8)?  Had he seen the Christ of faith?  "The attempt to throw upon the evangelists the responsibility of Christology does not survive a rigidly critical examination," write Hoskyns and Davey.  "Their records have a clear and conscious purpose.  That is obvious.  But they extracted their purpose from the traditions they received: they did not impose it roughly upon a material unable to bear it."

Source: Macleod, Donald. The Person of Christ. Downers Grove, IL: InterVarsity Press, 1998, pages 113-115.