1 Thes. 3:5 (ESV)
For this reason, when I could bear it no longer, I sent to learn about your faith, for fear that somehow the tempter had tempted you and our labor would be in vain.
It seems here, Paul, did not believe once saved always saved. He does think that the tempter can tempt a person out of faith.
He also fears that his labor would have been in vain. I think this is a place where pastors can stand up and take notice. Paul claims the Thessalonians as fruit of his labor. This is the same Paul that makes all those comments about faith being the work of the Holy Spirit. But the Holy Spirit works through people, or through the efforts of people. Perhaps this is what that cooperation of the Christian with the Holy Spirit in the sanctified life is all about. Sometimes, I wonder if us Lutherans don’t actually start thinking like enthusiasts when it comes to the work of the Holy Spirit. The Holy Spirit works through our work for the salvation of others. Sure, without the Holy Spirit working through the Gospel faith would be impossible. But without us proclaiming the Gospel, the Holy Spirit would be without a mouth piece. For sure he would find someone else. But there is no reason he can’t work through us. Unless we start thinking he is going to zap people on the street. We do have work to do, and it is more than the new building project.