Yes we do. In the Our Father we are taught by Jesus, "Forgive us our sins as we forgive those who sin against us" Hence we must do something to be forgiven.
Yes, but who forgive us first? We or God? Because God forgave us, we have to forgive. Otherwise God will claim our sins again. But first God forgave us and makes us able to forgive too.
When Jesus started His Catholic Church, He stated that the gates of hell would never prevail against it.
I see you believe that the catholic church is the only church. That is a unit of the catholic church. But when we look into the bible what is "church". The greek word Jesus used when he said to Peter, "I will built my church" is ecclesia. Ecclesia means Assembly. So Church is not an organisation, but a community, an assembly.
This church, the body of Christ, the hell can not destroy, because God protects it and God is more powerful than the devil. But Jesus Ecclesia consists of all those who gave their life to Jesus, but not of a special organisation.
I once preached about it. If you want I sent you the conception of this sermon.