Salvation, and thus missionary work, must be grounded in truth. The fundamental truth of all human affairs is that God's great love for us wills to save all men, and we must order our presentation of subordinate truths in a manner that will make them most credible. Missionary work, our proactive, evangelical share in this saving plan, requires patience, the Catechism tells us (CCC 854). That is because people are all coming from different places and experiences and will respond to different individual true statements in different ways; this also largely depends upon the person by whom they hear the truth proclaimed.
.... the salvation of souls - and not the simple proclamation of truth - is the highest law of the Church.
My summary of the whole thing:
1. There is a hierarchy of truths (all subordinate to Truth, of course)
2. Salvation of souls is the highest priority, not discrete "truth" (note: That does NOT mean you can lie or fudge for a good cause -- see #1)
From the Catechism:
Indeed, God "desires all men to be saved and to come to the knowledge of the truth";344 that is, God wills the salvation of everyone through the knowledge of the truth. Salvation is found in the truth. Those who obey the prompting of the Spirit of truth are already on the way of salvation. But the Church, to whom this truth has been entrusted, must go out to meet their desire, so as to bring them the truth.
I like it because it puts into clear wording something I was struggling with this summer.