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 rejected 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 die. 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.