Why is believing the only thing God asks?
Believing is the only thing God asks because every sin from Adam to the end of time was already paid for in full at the cross. God has already forgiven all people and reconciled the world to Himself, so He does not expect anyone to beg for forgiveness, but simply to believe it.
Les explains that if a person still had to beg for forgiveness, then the Book would be a lie, because all the mercy of God was poured out on the cross. God has already forgiven every human being all his sin; it was paid for in full. He does not expect someone to beg to be forgiven; He says you are forgiven. Believe it. The other word used in 2 Corinthians 5 is reconciled: the world has already been reconciled to God. Les points to Hebrews 2:9, noting that for every human being from Adam to the end of time, every sin has already been paid for. That is why the only thing God now asks is to believe it.