For if these qualities are yours and are increasing, they render you neither useless nor unfruitful in the true knowledge of our Lord Jesus Christ. (2 Peter 1:8, NASB)
This is a tough verse. I just don't get the way it is translated. Let's start with the verb, here shown as "render." Nowhere else in the NT it is translated this way. Elsewhere it is translated "appoint" (Lk 12:14), or "put in charge" (Lk 12:42), or, in the case of Jas 3:6; 4:4, it has the sense of "function in this capacity."
So, in the case of 2 Peter 1:8, "these things" (qualities is an interpretive addition) have been appointed. But "these things" is plural, and the verb is singular. It seems that "these things" actually should function, not as the subject of the verb, but as the direct object. "He" appoints these things for you. And who is "He"? It would be our God and Savior, Jesus Christ (1:1) or our Lord and Savior, Jesus Christ (1:11) that begins and ends this section. He has personally and authoritatively designed and ordered that a fully-supplied faith would have a powerful effect in our lives. It is not unusual to have an un-named subject. It is rather foolish to have an un-known subject. I think that subject is Jesus. Let's give him some credit.
Next, there is no "if" in the text. He appoints these things (the seven qualities in vv. 5-7) for you, to have a powerful and fruitful effect in your lives, with the result that you will have a deep and rich relationship (true knowledge) with him. This is not an "if" or "maybe" verse. It is not hypothetical or mere potential. It is a clear statement that serves as a powerful promise. Christian, this Person will grow on you. Work your faith; use it; develop it. It is a wonderful gift from above. And it will strengthen that heavenly relationship that you have with our risen and ascended Savior.
And, consider making a couple of pencil notes in the margin of your Bible alongside 2 Peter 1:8.