The Definition

In order to accurately determine if something is a sin, it is important to define sin.  Sin is not simply something that offends us or that we personally find unpleasant.  That is prejudice, not a good way to evaluate sin.  Here are a couple of tips for determining whether something is a sin:

Definition of Sin (from Merriam-Webster.com)

1) a : an offense against religious or moral law
b : an action that is or is felt to be highly reprehensible <it’s a sin to waste food>
c : an often serious shortcoming : fault
2) a : transgression of the law of God
b : a vitiated state of human nature in which the self is estranged from God
Biblical Defintion of Sin
Everyone who sins breaks the law; in fact, sin is lawlessness – 1 John 3:4
If anyone, then, knows the good they ought to do and doesn’t do it, it is sin for them. – James 4:17