Two thousand years ago, Hz. Isa (Jesus)did not exist. Can one add something to God later? Is God also so weak and helpless that He can be crucified by humans? Also, there are verses in the Gospels that show that Jesus was not willing to be crucified. (see Mt 27:46)
Answer: Theme 2 (The divinity of Jesus) and theme 5 (God, the three-in-one) have shown that in Jesus, the Messiah, the uncreated son of God became man a long time ago. Read: Heb 1; Eph 1; Col 1:12-20; Phil 2:5-11.
Read also Theme 3 (Cross, sin and redemption, III, 2 and 2.1).