Ephesians 4:32 And be ye kind one to another, tenderhearted, forgiving one another, even as God for Christ’s sake hath forgiven you.
Why forgive?  Because God said so!  If in fact you are a child of God, then you have experienced God’s mercy in forgiveness.  We all violated God’s law, thereby we are guilty of the whole law.   Think about standing before a judge in a courtroom as he begins to read every law of the land.  After each law is read, he drops the gavel and pronounces you GUILTY. The penalty is death.
Then a lawyer, an advocate if you please, steps from the shadows and says… forgive them, charge their sin to my account and place my righteousness on theirs. GLORY!  Been there, done that!
Jesus saved me that night!  Now, as you’re leaving the courtroom someone robs you.
Another comes behind him and beats you.  Another comes and strips you. All the while,  others are standing around mocking you and spitting on you.  If we truly understood what just happened in that courtroom, there would be a willingness to forgive each one.  Stephen did!
And yet, there are many miserable Christians walking around with a grudge in their heart. An unforgiving spirit.  Why forgive?  Because we’re forgiven!  Because we have prayers that need answers!  Because it grieves the Holy Spirit if we don’t forgive!  And, it brings great release and joy!  To forgive is to set a prisoner free, only to discover,  the prisoner was me.  Bless His Holy Name! Amen.  Pastor