The first Missionary Journey shows us that contending for the purity of faith is simply part of sharing the Good News of Grace! God not only saves sinful man; He works in, through and with sinful man. That is, indeed, GOOD NEWS!
Praise and persecution came as the missionaries testified of God's grace. The Good News elicits a response; it will not be ignored. Even the priest of Jupiter got excited--and Paul and Barnabas had to contend for the purity of the faith by pointing back to the grace of God. The unbelievers stoned Paul and assumed he was dead; the disciples rallied around him and he arose. Nothing is powerful enough to withstand God's grace. The missionary life testifies continually of that power. Paul and Barnabas, through their words and their actions 'confirmed the faith' of others. Living with confidence in the grace of God does that. Others' faith grows strong, so they can 'confirm' other disciples; it is the way His Kingdom advances.
Right alongside that truth is the truth that we never stop needing His grace. Sometimes the message we live gets muddied. Folks went out from Judea saying grace was not enough. Peter and Barnabas allowed 'peer pressure' to alter their testimony to the grace of God. Some Pharisees who became believers 'rose' up in the Church adding their traditions to grace. We all bring baggage into our faith; learning to live in grace is a challenge. That's part of contending for the faith; Paul demonstrates how.
The Word says Paul stood up and the disagreement was public--face-to-face. The devil's power is in darkness. When things come to the Light, the Holy Spirit can bring unity in diversity. It takes faith in Him...faith in His grace and power. Focusing on the mud is not the solution. It is the Light of the Word and the Love of God that we are to bear witness to. God calls different people to different ministries and as long as the message is consistent with the Word and Grace, it is okay!
So the sum of my take-away today: Grace allows God to use imperfect people!