Knowing the right thing to do and not doing it is a big mistake.
Read: James 1:22-25
But prove yourselves doers of the word [actively and continually obeying God’s precepts], and not merely listeners [who hear the word but fail to internalize its meaning], deluding yourselves [by unsound reasoning contrary to the truth]. 23 For if anyone only listens to the word [a]without obeying it, he is like a man who looks very carefully at his natural face in a mirror; 24 for once he has looked at himself and gone away, he immediately forgets [b]what he looked like. 25 But he who looks carefully into the perfect law, the law of liberty, and faithfully abides by it, not having become a [careless] listener who forgets but [c]an active doer [who obeys], he will be blessed and favored by God in what he does [in his life of obedience].