We like to relate with people who seem sincere.  We like to do business with people we think we can trust.  But, sadly, people are not always the same as they appear.  The false teachers who had invaded the Galatian churches did not look or sound bad.  They seemed very confident and sincere.  The believers thought that they were personally interested in them and had their good at heart.  Certainly, they were sincerely confident; but they were sincerely wrong - and the believers were being led away from Christ.
 
Paul was passionate about their spiritual welfare, even though the churches had rejected him and his gospel (Galatians 3:1-5).  But Paul knew that the seed of the gospel was still potent and would produce real spiritual life in some.  The inner pain of their spiritual defection matched the frustrated inner conviction that the gospel seed must be allowed to grow so that they would be properly formed into the image of Christ.  To Paul it was as personal and inescapable as labour pains to a pregnant woman.  They needed to desire Christ and allow Him to dwell in them so that they became like Him.

Many parents have similar heartaches if their children go astray.  They are convinced of their love for their child, clearly observing the error they are embracing, knowing that their influence is limited but longing passionately that their child return.  It is the story of the Prodigal Son (Luke 15:11-32).  That longing for sinners and backsliders to return is embedded in Father God’s heart.  It should be the pastor’s heart too (Philippians 1:8; 2 Timothy 4:1-5).
 
It is easy to be a religious enthusiast: just be totally convinced about a new idea you have had, be sincere and passionate, and sell your ‘product’ to people who will ‘buy in’.  Many people have done that, and some have made a lot of money.  But the Apostle Paul was different.  The gospel was not his idea (Galatians 1:11-12). He did not make any money out of gospel preaching (he chose to pay for his living expenses out of his earnings as a tentmaker).  He did not manipulate people and was not a very impressive speaker. But God used him to communicate the truth about Jesus.  Like Paul, when you are passionate about what is right and true, God will use you.  Otherwise it is like selling fake goods.