God is the super-duper metaphysical Being who created the universe and all that is in it. He transcends time and space because He created it, hence physical specks like us can't see Him or fully comprehend Him.

God loves humanity, but gave humans a choice to love Him back. Mankind collectively refused this offer when the universal representative (some dude called Adam) said 'no thanks bucko', culminating in everything going to the dogs and the world plunging into turmoil and suffering, which was fair enough really.

Nevertheless, despite being rejected by His own creation, God sent His Son to earth as a random called Jesus, who died the death we were meant to. If you are Jesus' friend and you bite the bullet, you can sneak past security with him at the pearly gates, but otherwise you're stuffed.