When you 'gently instruct' a MORMON; they pat you on the head, say "Thank you; run along now." and go merrily on their way.
Perhaps that gentle thing works AFTER you take a 2*4 to the noggin to get their attention first.
(Notice that REPENTANCE comes before KNOWLEDGE?)
“Son of man, I have made you a watchman for the house of Israel; so hear the word I speak and give them warning from me.
When I say to a wicked man, ‘You will surely die,’ and you do not warn him or speak out to dissuade him from his evil ways in order to save his life, that wicked man will die for his sin, and I will hold you accountable for his blood.
But if you do warn the wicked man and he does not turn from his wickedness or from his evil ways, he will die for his sin; but you will have saved yourself.
Again, when a righteous man turns from his righteousness and does evil, and I put a stumbling block before him, he will die. Since you did not warn him, he will die for his sin. The righteous things he did will not be remembered, and I will hold you accountable for his blood.
But if you do warn the righteous man not to sin and he does not sin, he will surely live because he took warning, and you will have saved yourself.” Ezekiel 3:17-21
Go into all the world and preach the Gospel to everyone. Those who believe and are baptised will be saved. Those who do not believe will be damned. Mark 16:15, 16