Been in 1 Thessalonians of late. How rich! One of the things I love about Paul's letters is the way he regularly combines doctrine and duty, belief and behavior, exposition and exhortation. Here's an overview.
We see this beautiful transition in 4:1, don't we?
Here Paul turns from the reception of the gospel (evangelism) to everyday Christian discipleship (edification). Moreover, he's not only concerned with personal ethics. He wants to depict in very clear terms the characterization of the new community that Jesus brought into being by his death and resurrection.
The basis of Christian ethics is clearly spelled out here. For Paul, Christian moral duty is above all pleasing God. We're not to think of our Christian duty as law but as love. Hence the Christian life is not primarily about obeying rules and regulations (though Paul does lay down quite a number of instructions in chapters 4-5). The Christian life is primarily a relationship. It's about pleasing a person. The God who made me, loves me, sent his Son to redeem me, adopted me into his family, and placed his Holy Spirit in me, is my loving Father -- and I want to please him. This is the essence of Christian holiness. Our greatest desire in life is not to please ourselves or to please others. It's to please our God. I think I can say that this is the main reason I exercise.
Have you gotten hold of that yet? If we love God, we will please him. And we will do this more and more. You say, "How can I, at 74, continue to please God more and more? I'm too old for all that. I've maxed out my potential to grow." The result, sadly, is often complacency as we age. What a horrid thing. Beware of saying that you have arrived. Beware of saying that you don't need to grow or improve any more. Beware of downright laziness in your Christian walk. We are to please God more and more and more and more in spirit, soul, and body.
What a liberating principle by which to live! It rescues us from a kind of Christian Pharisaism that reduces ethics to a list of do's and don'ts. Our incentive is not so much to obey the law as to please the Law-Giver.
Paul was never satisfied with the level of spirituality to which he had attained. Neither should we ever be.
P.S. Interested in studying 1 Thessalonians on your own? I've put together a guide here (scroll until you see "The Literary Structure of 1-2 Thessalonians").