How should a christian evaluate whether a particular action a sin or not?

Question

Since they are directly addressed in the ten commandments, most people agree that committing adultery or murder is sin; yet this world is a complicated place full of things that are not so clearly addressed. Some traditions believe using electricity or wearing pants are sins, others do not go so far.

What guidelines can a Christian use to evaluate whether a specific action is sinful or not?

Answer 1

Sin as a condition is separation from God. A sin as an action is an action that brings about such separation from God; such an action "misses the mark," which is the Greek word for the act of sinning. This is the general---very general---rule of thumb. The trick is to tell what separates us from God.

A good rubric, for those who already know in their heart of hearts what is right and wrong, is that given by Mississippi comedian Jerry Clower in his album Classic Clower Power, disc 2, track 25 "You're Fixin' to Mess Up" (cf. http://jacksonianlawyer.wordpress.com/2009/07/25/some-sage-words-of-advice-from-the-legendary-jerry-clower/). For the sake of those yet unable to endure heavy Southern accents, here is the rubric distilled:

If you’re fixing to make a decision about what’s right and what’s wrong in your life, do you ask other people’s opinion about it? That’s a pretty good indication you're fixing to mess up.

Number two: do you argue with yourself? ...if you’re arguing with yourself, [that's a] pretty good indication you should not do it.

Number three: do you feel uneasy when you do it?

Number four: Can you give thanks and say ‘Lord, I thank You for providing this for me.’? The Bible says, give thanks for all things. So when you do it, can you say ‘Lord, thank You for providing this for me. [Indeed, I thank You] for [making things the way they are, so that] I can commit to what it is I’m doing.'?

What is right or wrong? Do you ask other people? Do you argue with yourself? Do you feel uneasy when you do it? Can you give thanks and say ‘Lord, I thank You for providing this for me.’? If you can’t, you [had] better watch out…you’re fixin’ to mess up.

N.B. in Southern dialect, to be fixing to do something is to be about to do something.

At the root of sin is self-will and insistence upon our own way at the expense of submitting ourselves to our Father in heaven Who knows better. The resulting cognitive dissonance brings about the signs 1--3 above.

Edit: as @Jürgen A. Erhard has pointed out, this rubric is insufficient on several counts. In my opinion, this is because it displays the signs of cognitive dissonance, which (thank God) accompany a struggle with temptation. These signs are useful in a sort of basic triage to call oneself to attention: if experiencing the signs in this triage (or quadriage), mustering all your dispassion, immediately ask yourself, "Have I committed to doing something wrong, and am I now only trying to justify myself and my wrong actions?"

However, cognitive dissonance may also accompany any difficult decision, which is not necessarily a result of wrongdoing. Also, weighing both sides of a difficult decision is, presumably, an attempt at wisdom and not an attempt at self-justification; and furthermore, asking someone else (whom you respect as someone following the truth, not just someone whom you know will agree with you) is a manifestation of humility. So perhaps at the root of Clower's observation is that one must flee all appearance of sin: in particular, the self-justification that accompanies an assent to sin.

This is a way to tell if you are doing wrong. It is another story to tell what is right, i.e. what is best.

Answer 2

Sin is lawlessness

God has given us commands based upon His nature. Meaning that the right thing to do is based upon what He would do and the wrong thing to do is against what God would do.

1 John 3:4 NKJV

Whoever commits sin also commits lawlessness, and sin is lawlessness.

The new testament puts a spin on law, instead of us following the law, we are now to follow exactly by Jesus examples. Basically, living by faith has replaced the need to live by the law. So what is sin today?

Romans 14:23 NKJV

But he who doubts is condemned if he eats, because he does not eat from faith; for whatever is not from faith is sin.

Whatever is not from faith is sin.

Instead of looking to the law we now look to Jesus. But remember, the law is based off of Jesus nature and Jesus followed the law to the letter. So sin is still to not follow the law, but it is also to not follow Jesus.

Answer 3

Sin does require full knowledge that the particular action is sinful.

Whenever evaluating something as sinful you must take into account the

1. Circumstances:
   1. Killing out of self defense
   2. Righteous Anger (not self directed, but in protection of others)
   3. Had no way of grasping the moral/ethical reality. (this could be said of lots of cohabitating couples today)

2. Object:

   What is the thing being acted on. These are the 'Ends'. If one does harm to a completely innocent creature, then you're committing a 'graver' sin than if you do something to a mostly innocent creature. (Difference between exterminating rats in your basement and hitting them with baseball bats for fun)

3. Intention:

   Ends cannot justify the means, but the intention is important. If you start out with bad intentions, it really doesn't matter what good you do, although hopefully you'll learn that doing good is much better than doing evil!

This is what I taught to my 8th and 9th graders last year in Religious Ed. it comes out of a faith formation handbook for teenagers from St. Mary's Press.