What's the easiest way to explain justification in your opinion?
First of all, we explain justification n terms of a court case. Justification is a legal term. It is what happens when a judge declares that the person on trial is innocent of any crimes that he has been accused of.
There are other meanings for the word justification. It might be helpful to explain them. Justification, secondly, is also what happens when we make a claim, and attempt to back it up with proof. For example: I could say that the best poutine in Quebec is found at the "roulotte de patate" in Gentilly. What would it take for my claim to be "justified"? Proof! So, justification is also what happens when we prove the truth of a statement.
Justification, in a third sense, can also mean the process of making a person become just. In contemporary protestant terminology we use a different word for this process, "sanctification", the process of being made saint or holy (In French the word saint is translated, in English, by the word holy.). (Small rabbit trail here - This third sense is part of the confusion between Catholic theologians of the Middle Ages and contemporary Christians. Quite frequently Catholic theologians in the Middle Ages used the word Justification in this third sense. However, most contemporary Protestants understand the word justification in the first sense (using the word sanctification to talk about this third sense of justification). So, when we read it in the writings of medieval theologians we read that "we are 'justified' by works" and we cry "heresy". However, quite frequently, all that they are saying (this all depends on properly understanding the context) is that a human being is made into a just person (justification of his character) by doing just works. This is biblical teaching.)
Paul is constantly telling us to imitate him as he imitates Christ (1 Cor. 11:1). Philippians 4:8-10 is all about thinking rightly and acting rightly in order to have right thoughts and do right actions. Our character is formed, through the power of the Holy Spirit, by our actions (2 Pet. 1:3-10). The whole point of the book of James, especially chapter 2, is that our justification, being made into just people, is not just a question of a "workless" faith. Rather, in order to be made into a just person we need to do just works. Being made “just before God” (which is the first sense) happens by faith alone. Becoming a person who is just, in character, is a result of just actions accomplished through the power of the Holy Spirit (2 Pet. 1:3-11).
Anyways, just some food for thought.