A few years ago I was sitting in a church history class in seminary. The professor was lecturing on the debate between Athanasius and Arius regarding the divine nature of Jesus Christ. A fellow student raised his hand, identified himself as a future missionary, and asked with, no small level of disdain, how this would help him be a better missionary. The professor did a fine job of explaining how theology undergirds ministry--but I'm not sure the student bought it.

I never saw another incident like that while I was at seminary. I remember it because I understand it. My mind gravitate toward that which is obviously and immediately relevant. Being a Christian (and certainly a Christian serving as a missionary) requires us to reflect upon who Jesus is and what he has done even before we answer how this affects us. We must answer the latter, but we must first dwell on the former. 

Could this be why Peter exhorted "those who through the righteousness of our God and Savior Jesus Christ have received a faith as precious as ours" to add to their faith certain things, including knowledge?

For this very reason, make every effort to add to your faith goodness; and to goodness, knowledge; and to knowledge, self-control; and to self-control, perseverance; and to perseverance, godliness; and to godliness, brotherly kindness; and to brotherly kindness, love. For if you possess these qualities in increasing measure, they will keep you from being unproductive in your knowledge of our Lord Jesus Christ (1 Peter 1:5-8).