Two lines in the Lord's Prayer say,"Forgive us our trespass, as we forgive those who trespass against us" so look at what it says. If we forgive other people their trespasses then God will forgive us. If we do not forgive other people their trespasses then God will not forgive us our trespasses. Where will we go for eternity if God does not forgive our trespasses? Any unforgiven sin will send us to hell.
Go to incest-information.coffeecup.com to discover one sin Jesus said God would not forgive.