Christa is an idol; she is the invention of feminist theologians who smuggle her in on the back of Jesus' humanity. The thoroughly secular ideological assumption behind such feminist theologising is that Jesus' humanity, if it is to be truly inclusive, must acknowledge a feminine side. This feminine side to Jesus can be explored through 'theology' (in this case of the speculative kind) and through the creative arts.
Holy Scripture acknowledges no such person as Christa, but proclaims Jesus Christ, the Son of God. Reflecting the teaching of the Bible, the Nicene Creed, included in the service of Holy Communion according to the Book of Common Prayer, expresses the belief of the Holy, Catholic and Apostolic Church in 'Jesus Christ, the only-begotten Son of God, begotten of his Father before all worlds, God of God, Light of Light, Very God of very God, Begotten not made, being of one substance with the Father, by whom all things were made’. The Creed is clear that it was God the Son who ‘became incarnate by the Holy Ghost of the Virgin Mary, and was made man’ for our salvation.
For Nicene Christians the fact that Jesus was a man and not a woman is hugely significant. As man he was able to save both men and women. If he had been a woman, then he would have been able to save nobody.
That is because of the biblical significance of the first man Adam, whose effect on the whole of humanity Jesus has reversed. As the Apostle Paul argues in Romans 5:
But the free gift is not like the trespass. For if many died through one man's trespass, much more have the grace of God and the free gift of grace in that one man Jesus Christ abounded to many. And the free gift is not like the effect of that one man's sin. For the judgment following one trespass brought condemnation, but the gift following many trespasses brings justification. If, because of one man's trespass, death reigned through that one man, much more will those who receive the abundance of grace and the free gift of righteousness reign in life through the one man Jesus Christ (Romans 5v15-17 - RSV).
As the first man, Adam was the federal head of the human race and brought it down with him. As the federal head of the new humanity, the man Jesus Christ brings all male and female believers in him the saving grace of God. The salvation the second Adam achieved for lost humanity is expressed beautifully by Cardinal Newman in his celebrated hymn:
Praise to the holiest in the height,
and in the depth be praise;
in all His words most wonderful;
most sure in all His ways.
O loving wisdom of our God!
when all was sin and shame,
a second Adam to the fight,
and to the rescue came.
The biblical logic is thus this: if Jesus Christ had not shared Adam's maleness, then the salvation he brings would not be inclusive. So thank the good Lord Jesus was a man and not 'Christa'.