While examining David's life, some friends pointed out the "offense of Grace."
David's lamenting of Absalom was an offense to Joab. David's extravagant love that kept coming in spite of the sin of Absalom, is a groaning identification, a desire to take the place of the object of love. Grace offends, it is free and sovereign. God's love for those who do not love Him yet is costly to those who do love Him. If we think we have some "claim" on God's love, we are set up for pride and a fall. The older brother appears to have a right to be offended, until you consider that "all that I have is yours." What I give to the prodigal son, does not rob anything from you. Grace is an intended, built in offense, to examine how we view the grace that WE have been given.
Grace is deeper and wider than we can know in this life and we will spend eternity learning about it and a true understanding of His grace and mercy will compel us to love and obey Him more, not less.