The cross is meant to be one of those things that drives our emotions. What we love is what we “boast” about the most. You can get all emotional and teary eyed about lots of things in this life, but there is one thing that is supreme among them all,“God forbid that I should boast except in the cross of our Lord Jesus Christ.” John Stott explains the meaning of the word boast: “It means… to boast in, glory in, trust in, rejoice in, revel in, live for.”

What you boast about is what you like; what you have affection for; what you think about; your hobby horse; what gives you a sense of satisfaction; what makes you swell with pride; what makes you happy; what you rejoice in.

Paul is saying, "This is what the cross should be for you." It should be the primary object of your affections. Paul is wrestling with the saints in Galatia that it not happen that their lives would be centered around anything else but the cross.

To say, “God forbid” is like saying, “May it never happen to me.” This is a good prayer for ourselves and our churches.