Which Christianity continues in that error?
Jesus, the Son of Man and God, was God, and human, by nature. Not in Person. Yet in person. The most complex entity, the hypostatic union, ever envisaged. But not an absolute impossibility. Not a Person of God collapsed from beyond infinity, after eternity, to a sperm. That is meaninglessly absurd, absurdly meaningless. Get rid of that non-sense, that dis-order, and you could make more sense, order of Jesus, God incarnate.
At conception the nature of God suffused a human. The light of God the Son shone in to, through, a Spirit fertilized ovum sized window. A window that grew to a man and the light of God the Sun intensified a billion times through that human portal. On death the window was shuttered. Winked out. On resurrection, by the Spirit?, the window opened to infinity. That’s how I make tenuous order, sense of Him. YMMV. As for what He is now, that can wait.
(A Person of) God cannot die. Any more than they can become a sperm.
It’s irrelevant how long He was dead. And the old wives’ tale was Jesus’ of Jonah.