But if you harbor bitter envy and selfish ambition in your hearts, do not boast about it or deny the truth.
The "bitter envy" could also be "bitter jealousy", not sure if that helps. Studylight.org adds this to the definition of "selfish ambition": "This word is found before NT times only in Aristotle where it denotes a self-seeking pursuit of political office by unfair means." I thought that was interesting, and helps to understand the idea behind the "selfish ambition."
The Adam Clarke Commentary offers this help:
If ye be under the influence of an unkind, fierce, and contemptuous spirit, even while attempting or pretending to defend true religion, do not boast either of your exertions or success in silencing an adversary; ye have no religion, and no true wisdom, and to profess either is to lie against the truth. Let all writers on what is called polemic (fighting, warring) divinity lay this to heart. The pious Mr. Herbert gives excellent advice on this subject:-
"Be calm in arguing, for fierceness makes Error a fault, and truth discourtesy; Why should I feel another man's mistakes More than his sickness or his poverty? In love I should; but anger is not love, Nor wisdom neither; therefore g-e-n-t-l-y m-o-v-e."
That bit of commentary really cleared things up for me. I will admit it, maybe it is because I am tired or because it is the end of the school year, but I was having some trouble coming up with some thoughts on this verse. Now, I am actually finding it to be beneficial in my circumstances. Praise the Lord for smarter people who have done a good work that we can draw from.