Zac Poonen emphasizes the necessity of mercy and forgiveness among believers, highlighting that our human nature often leads to unintentional harm to one another. He warns that harboring unforgiveness creates a 'little bit of hell' within us, which can hinder our relationship with God and even affect our physical health. Poonen stresses that true forgiveness requires brokenness and a desire for reconciliation, urging us to pray for the forgiveness of others as we seek our own. He reminds us that without forgiving others, our prayers may go unheard by God. Ultimately, the call to forgive is a reflection of our own need for mercy and a vital step towards spiritual healing.

We all have a flesh and we are living among others who have a flesh. And so we are constantly liable to injure one another knowingly and unknowingly. The only place where we'll never get hurt by anyone is in heaven. And so we need to forgive one another as long as we live on this earth. To err is human, to forgive is divine. One of the features of hell is that there is no mercy there. And in the measure in which you lack mercy in your heart towards others, in that measure you have got a little bit of hell right inside your heart. If you are unwilling to forgive someone, you've got a little bit of hell inside you. You may be considered very pious by others, because of all your religious activity. But you've got this little bit of hell right inside you all the time. And you can't go to heaven in that condition - because you can't take hell into heaven. You've got to get rid of it before you leave this earth. That's why the Lord taught us to pray, "Forgive us in exactly the same way that we have forgiven others." When we don't forgive others, it can affect our bodies too. Disobedience to God's laws often brings physical suffering. If you bear a grudge against someone in your heart or if you're jealous of someone, and thus violate God's law of love, it can finally begin to affect your body. There are Christians today suffering from arthritis, migraine, rheumatism and asthma etc., who can't be healed - just because they have a grudge against someone. They may take any number of pills but they're not going to be healed until they learn to forgive. The cause of such diseases is not organic. It's not in their body. It is in their soul. If you have not forgiven your brother or sister, God will not listen to your prayer. The Bible says in Psalm 66:18: "If I regard wickedness in my heart, the Lord will not hear." It's not only that He doesn't answer, he doesn't even HEAR. Let's not fool ourselves. True forgiveness follows brokenness and confession, and that involves a recognition of the rottenness of our flesh, a willingness to make any restitution and to ask anyone's forgiveness if necessary, if only our relationship with God can be straightened out. In Mat.6:12 Jesus taught us to pray "Forgive US." We want our brothers to be forgiven too. Sometimes, it's possible to have a secret hope that a brother will be judged by God for the way he has treated us. Such an attitude is Satanic - for it's only the devil who wants people to be punished by God. Jesus said, "I have washed your feet and you must wash one another's feet" (Jn. 13:14). That means that when you see dirt on your brother's feet (spiritually speaking), you must long for him to be cleansed too. "Forgive US" means, "Father, I won't be satisfied if you just forgive me my sins. There are other brothers and sisters around me. I want you to forgive them their sins too. Amen."