It is good to expose what is false and teach what is true. The Bible holds the truth of God. Adding to it is wrong.
If you could help lead a friend from a life leading him or her to hell, wouldn't you jump to teach them the truth.
Before I was saved, I decided that I wanted to follow the truth of God and not man. I did not want to be deceived. The Bible led me to God’s truth.
Ezekiel 3:18,19 (KJV)
18 When I say unto the wicked, Thou shalt surely die; and thou givest him not warning, nor speakest to warn the wicked from his wicked way, to save his life; the same wicked man shall die in his iniquity; but his blood will I require at thine hand.
19 Yet if thou warn the wicked, and he turn not from his wickedness, nor from his wicked way, he shall die in his iniquity; but thou hast delivered thy soul.