So then (αρα ουν). Two inferential particles, "accordingly therefore."

Let us follow after (διωκωμεν). Present active subjunctive (volitive). "Let us pursue." Some MSS. have present indicative, "we pursue."

The things which make for peace (τα της ειρηνης). "The things of peace," literally, genitive case. So "the things of edification for one another" (τα της οικοδομης της εις αλληλους).