Jesus taught that prayer must be with forgiveness (Matthew 5:23, 24; 6:14-15; Mark 11:25-26)
In these passages Jesus seems to be teaching us that if we have not forgiven someone we may as well not pray at all. Mark 11:26 says, “If you do not forgive, neither will your Father in heaven forgive your trespasses.”
Jesus is not saying here that if you don’t forgive others you have lost your salvation; but He is saying that in your unwillingness to forgive someone you have cut off your fellowship with God. Why? Because in your sin against others (in not forgiving them) you sin against God too. Sin always separates us from God, and so this is why when we sin He will not regard our prayers (Ps. 66:18, Jn. 9:31).
Now we know that there are many different kinds of sin, and all of them, if unconfessed will separate us from God and will hinder our prayers. So why does Jesus point out this particular sin of unforgiveness? Well, I suggest that it is because this sin is perhaps the hardest to get rid of. For this sin is not just with ourselves, it involves others. So to get rid of it we must take steps toward others and with others to reconcile. And the longer we wait the deeper the bitterness sets in, and so over time it becomes so so hard to be free of. And Jesus knows this, and so this I think is why He has made a point of it here in these verses. For He doesn’t want us to become bitter and therefore to be separated from Him. He wants to be in continual fellowship with us and wants to hear our prayers.
I like what Paul said in Acts 24:16: “…I myself always strive to have a conscience void of offense toward God and men.” Paul knew the value of having a clear conscience toward God and others and how it was so necessary for prayer. Let us make that our goal too.