Matthew 18: 15 - 35  Jesus is teaching His disciples that greatness is not about power or position when it comes to the Kingdom of heaven... but about humbly serving others...the little ones and the lost.  Jesus goes on to teach them about forgiveness.

Verses 15-20  reveal God's plan for helping each other when one falls away due to sin.   We are, first of all, told to go privately to our "brother".  "... if he listens to you, you have won your brother."  
If that does not work, then 2 or 3 brothers are to go together and speak to him.  It is important that the facts are confirmed.  Only then, if the person refuses to listen or repent, does the matter go before the church as a whole.  Finally, if the person won't turn from their sin, are they removed from the church.

Jesus gives the disciples a powerful responsibility here. " Truly I say to you, whatever you shall bind on earth shall be bound in heaven; and whatever you loose on earth shall be loosed in heaven. "  From what I have read, this idea of binding and loosing has to do with condemning or forgiving.  The Holman Bible Dictionary states that "Heaven sets the standard and earth follows heaven's lead."  The church either "binds" or condemns the sinner... or it "looses" or forgives him... based on the sinner's response when reproved.  This gives us a different perspective to the next 2 verses, " Again I say to you, that if two of you agree on earth about anything that they may ask, it shall be done for them by My Father who is in heaven .  For where two or three have gathered together in My name, there I am in their midst."   

Perhaps we have been misusing this verse?  In this context, the agreement is about binding or loosing... not about asking for things.  It is about condemning the sin... of an unrepentant individual, or forgiving and restoring into fellowship one who has listened and repented of their sins.  It is a decision that must be based on Heaven's standards.  It must be decided in agreement and unity with the Lord Himself. This is a serious and sacred situation.  It is truly life or death... for the soul of a brother is at stake.

(Verses 21-35)  Peter's question about forgiveness takes on a deeper meaning in light of the above thoughts... If the one who sins does repent and is forgiven... what happens if he sins again?  " ... how often shall my brother sin against me and I forgive him? Up to seven times?"   No, Jesus says, "I do not say to you, up to seven times, but up to seventy times seven." 

Again, Jesus goes deeper... He  teaches a totally different idea about forgiveness... that goes beyond numbers, beyond the surface.. " The kingdom of heaven" ... looks at forgiveness in this way... like
a king  who is settling accounts with his slaves and one comes before him owing ten thousand talents. This is an astronomical debt - $10,000,000 worth of silver.  The man could never in his lifetime pay this back.  When he begs for the king to have "patience" and to not sell him and his family, the lord "felt compassion and released him and forgave him the debt."  He was free from the debt and from the punishment.  "Loosed"!

However, that is not the end of the story.  The slave goes out from the king's presence and finds a fellow slave who owed him a "hundred denarii" - one day's wages.  He chokes the man.  He refuses to listen to his plea for patience. He throws him into prison.  He will let the man stay there until somehow he is repaid.  He "binds" his fellow servant.

When the other slaves witness this, they are "deeply grieved".  They report to the king about what has happened. The king calls the  first slave back in and this time he is condemned... not for his debt, but for his unforgiveness and lack of mercy. " And his lord, moved with anger, handed him over to the torturers until he should repay all that was owed him. " The debt that had been forgiven was now owed once again.  The man was "bound" because of his failure to "loose" his brother.

Jesus says " So shall My heavenly Father also do to you, if each of you does not forgive his brother from your heart." 

To forgive - to send away, separate , lay aside, yield up - the debt, the sin, or the trespass of another.
This is such an important part of what Jesus teaches about the Kingdom of heaven.  In Matthew 6 Jesus taught His disciples to pray, " And forgive us our debts, as we also have forgiven our debtors."
 ( v12)  He went on to say, " For if you forgive men for their transgressions, your heavenly Father will also forgive you. But if you do not forgive men, then your Father will not forgive your transgressions." (v14-15)  This is perfectly illustrated in the parable of Matthew 18.

Father in heaven, You alone are worthy of all glory and praise.  You are faithful and You are willing to forgive us the great debt that we owe and can never pay on our own.  Thank You that Jesus has paid it all!  What marvelous grace and mercy You have lavished upon us!  I choose now to forgive every debt and trespass that has been done to me and release them into Your hands.  May Your will be done and Your Kingdom come Lord! Amen!