Summary
Even if we already love our brothers and sisters in Christ, we can always do so more fully. We need to guard against thinking we’ve “made it” and have no more need for improvement in this area, just like all other areas besides. For the second we stop straining ever forward and put down our sword, at that moment our self-delusion will cripple our spiritual growth greatly. Because “the healthy” (in their own opinion) don’t even think they need a doctor, they cannot ever get better (cf. Luke 5:31-32; Revelation 3:17).
Content
In 1 Thessalonians 4:10, Paul encourages the Thessalonians to continue to love all of God’s family throughout Macedonia more and more.
We can always love more fully, even when we actually already are loving others (compare the first half of the verse)—and that is no low bar to clear in itself! This is actually rather important as a concept, because it means love is not binary, but a continuum. We all have more work to do here, even if we fancy ourselves as already spiritually advanced. If we ever think we have “made it”, we need to check our attitude.
I think perhaps it is easy to think of those in our lives that are easier for us to love—perhaps our spouse, our children, our families, and our friends who already love us in return—and then conclude that we do love other Christians as we ought. But what about everybody else around us in our church communities? We can’t stretch the context here in 1 Thessalonians 4 to include unbelievers since the text is very obvious talking about believers (“God’s family in Macedonia”), although we certainly need to love unbelievers—just as God does—in that we should desire their salvation and repentance. Even without including unbelievers, however, I am sure most Christians can think of a few people they know who profess Christianity (and may well be actual believers) who nonetheless are not easy for us to love, for whatever reason.
And this is why we all have work to do here, why it will always be a constant battle to love our brothers and sisters in Christ more and more—because selfishness and pride come much more naturally to us than service and humility. We must stay honest about the need for continual growth and progress here (as in other areas), to guard against legalism and an improperly inflated estimation of our holiness and accomplishments. Honesty with oneself is quite critical for us as Christians to make maximal forward progress; self-delusion affects all of humanity, Christians included (see here, for example). This area of growing ever more in our love for the brethren is a great example of the importance of avoiding self-delusion in our own walks—of thinking that we are “doing good” when in fact there is still a vast chasm between where we are and where God wants us.