Don't know if that anon to whom you were replying is a believer on Jesus Christ or not,
but that question is not technically incorrect.
Jesus Christ didn't "become" God.
Jesus Christ was God from the moment of conception.
Saying He "became" God implies that at one point Jesus was merely a man,
who at some point later became God.
The proper way to describe it, is that God was made flesh.
God was incarnated.
He took upon Himself humanity.
To say Jesus became God, after first being merely a man,
describes reincarnation in that a thing of this creation is changed by being deified.
God entered into His creation by being made flesh.
He did not inhabit another autonomous creature to make that creature into something else of which it was not originally.
That would be reincarnation, not incarnation.
Therefore, Jesus Christ the Man was God from the moment of conception.