Luke 17: 1-4  Jesus tells His disciples and us, " It is inevitable that stumbling blocks should come..."  - the greek word here is skandalon - scandal - a trap or snare; a cause of stumbling or offense; an enticement to sin. Things that  will trip us up.

 The one who causes the other to stumble will be judged and it "would be better for him if a millstone were hung around his neck and he were thrown into the sea, than that he should cause one of these to little ones to stumble." ( Verse 2).  These are pretty serious words!  It would be better to suffer a violent death than cause someone else to stumble into sin. So...

 "Be on your guard!...." Jesus tells us, "... If your brother sins, rebuke him; and if he repents forgive him.  And if he sins against you seven times a day, and returns to you seven times, saying, 'I repent' forgive him." ( verses 3-4).

Be on your guard.. so that you are not a stumbling block!  We do that by forgiving.... even if that means we do it over and over and over again!  What kind of person can really DO that?  Only the one who has received forgiveness himself.  Only when we have humbled ourselves before God and have repented of our own sins; when we have understood the fullness of the grace He has lavished on us; and when we have opened our own hearts to His glorious light;  only then will we be able to forgive those who have sinned against us over and over again... 

If we aren't on our guard, we will stumble.  We will hold their sins against them and allow bitterness and anger to take over our hearts.  We will fall.

Be on your guard - prosecho - hold the mind; pay attention to; be cautious about; apply oneself to;
" Do not be conformed to this world, but be transformed by the renewing of your mind, that you may prove ( discern) what the will of God is, that which is good and acceptable and perfect." ( Romans 12:2)  To be on our guard against stumbling or against becoming a stumbling block... we need our minds renewed.. set on His Word and His Will.  On that which is good and acceptable and perfect. 

Father in Heaven,  renew our minds!  Transform our lives! Fill our hearts with Your grace and mercy so that we will forgive others even as You have forgiven us our sins.  We cannot do this by our own will power.  We struggle to forgive even 1 offense, let alone 7 or 70... but in Christ our Lord we have strength. He is our model of forgiveness. Make us like Him! You are faithful and You have promised to establish us with Christ and anoint us and seal us by Your Spirit Who You have given to us as a pledge. To Your glory we ask these things. Amen.