The first and great sin of man is to NOT love God.
Without LOVE you have separation and enmity; and being just you alone you seek to do your own fleshly desires. You know, "me, myself, & I", the wholly triune-ity of self. This went on for hundreds of generations, and you STILL think very highly of yourself! God didn't go away, but He was severed from the spiritual connection that made direct communication with Him impossible. So, whenever God found anyone who didn obey and love Him more than self, God sent them to give a message to the others, --called a "prophet".
But what God needed was a new and perfect man, one that would act as a "proof of concept". For this, he must have perfect sinless blood, perfect obedience, and perfect love for God. This was a tall order, and after hundreds of years of finding no perfect man, God had to create one in a woman, who named Him Jesus, who became "The Perfect Atonement" for ALL of man's mistakes. And it was a perfectly BLOODY sacrifice, one that sinful man had decided was necessary to be redeemed. (goats, lambs, bulls, etc.)
So Jesus "perfectly" died as proof that sinful man could be reunited with God. But God needed a LIVING sacrifice, so He raised Jesus up for all to see. --See?