One man fell in Genesis 3. That put a great divide, a great separation between God and man. Adam and Eve tried to cover themselves with fig leaves that God was basically representing that man was trying to come to God on his own. God completely rebuffed that and In Genesis 3 15 which is known as the proto-evangelium God promised that a mediator would come he promised that a Savior would come That was the very first glimpse of the gospel then the whole Testament really points toward the coming Messiah. We needed a Messiah.

We could not fix the sin problem ourselves. And so God in His love and His kindness and His grace and His mercy sent Jesus Christ just at the appropriate time so that we could once again have fellowship with God the way that God intended fellowship to be had with Him ever since the very beginning. So Jesus Christ had to be our mediator. We couldn't do it by ourselves, which basically every other religion in the world says that we can earn our way to God. But God says, no, it won't be by man's own effort, it will be by my divine grace and mercy." And so God sent his son at the appropriate time.