Jesus was God clothed in flesh meaning it was only the flesh that died and not the spirit, so God did not die not even for a fraction of a second. For Christians there are two deaths. The flesh death which means the body that you or I occupy stops working and the spirit it contains leaves the body so the body returns to dust or back to the earth. The second death is the destruction of the spirit by God when those whose name is not found in the book of life have their existence blotted out. Because of Jesus being God death has no power over him because in the end death will also be destroyed.