Because he exists whether i believe he does or not. My personal beliefs or opinion have no bearing on the absolute fact that God exists, and since God is the very incarnation of Truth, i see no point in lying to myself, and would much prefer to follow the ultimate source of good, and have a firm belief and faith in him, that i may continue to know the truth. The reality is that any person who claims to not believe in God, has a reason to not want God to exist.
because he is the way the light and the truth. he is the only explanation for how we got here and why we are here no one will be permitted a second chance. This earthly life has been provided by God for all human beings to determine where they wish to spend eternity.