St Paul's letters write about things that are vital to our faith and Christian life: evangelism, mission, the meaning of Christ's death, the Lord's supper, baptism, resurrection and more. And in those same letters he is known to greet people by name. In his letter to the Romans, he greets over two dozen people by name (see Romans 16:1-16). Again there are around a dozen people listed in the closing of the letter to the Colossians, either co-workers of Paul's*, or those in Colosse. Paul shows no signs of embarrassment for mixing personal greetings with deep theology: he considers that people are worthy of acknowledgment and greeting. Paul did not write his letters for his own benefit but for theirs.
The weighty matters in his letters find their meaning only in relation to people, whether it is evangelism or mission, the meaning of Christ's death, the Lord's supper, baptism, or whatever the case may be: all these things involve people by nature, by intent, as their goal and purpose to call and uplift and restore people. And like Christ, Paul makes a point to know peoples' names. He recalls their names, notices people, includes people. When the Lord restores our souls, it is clear enough that people matter to him. They matter to his followers. They matter to us. People will matter til the end of time, and past the end of the age.
Christianity has a theological richness and depth, knowledge and wisdom -- and yet it cannot be confined to the academic. The Christian life is one of breaking bread and fellowship too. It changes daily life; it enriches daily life. An academic pursuit may be satisfied with information; Christianity is fulfilled with community and fellowship in our love of God and neighbor. It is more godly to pursue the lost soul than the lost fact. The lost souls are found by knowing them and being kind to them, and first of all by seeing and hearing them. It is a sign of respect -- of recognizing someone's worth -- that we know them by name. Those who taught us have set an example, and it is not for us to neglect it: we matter to each other.
* As he writes to the Colossians, Paul's list of co-workers includes both Mark and Luke. I've long found it worthy of notice that three of the known authors of the New Testament are listed together as co-workers in the same city at the same time. It would be possible for them to have sat around the same table there in Rome, and at least Paul was likely working on his writing projects. The New Testament writings themselves have an undercurrent of fellowship.