How could God die?
God did not stop existing. The eternal Son took on a real human nature and died in that nature, then rose. That is why his death can pay for sin.
Jesus said no one takes his life from him: he lays it down and takes it up again. His death was real, his body was buried, and on the third day he rose. Only someone who is both truly man and truly God could die for us and conquer death.
17Therefore the Father loves me, because I lay down my life, that I may take it again. 18No one takes it away from me, but I lay it down by myself. I have power to lay it down, and I have power to take it again. I received this commandment from my Father.”
John 10:17-18 (WEB) · context
6who, existing in the form of God, didn’t consider equality with God a thing to be grasped, 7but emptied himself, taking the form of a servant, being made in the likeness of men. 8And being found in human form, he humbled himself, becoming obedient to the point of death, yes, the death of the cross.
Philippians 2:6-8 (WEB) · context
3For I delivered to you first of all that which I also received: that Christ died for our sins according to the Scriptures, 4that he was buried, that he was raised on the third day according to the Scriptures,
1 Corinthians 15:3-4 (WEB) · context