It wasn't directed at you and I agree that scripture is certainly not legalism... but... when somebody says you will go to hell if you don't.... then that's legalism.
But I should point out that when someone comes to you trying to preach a different religion, like mormonism.... I do believe there might be more of a moral obligation to correct them... but I don't think one will go to hell if they don't.
Ah, mkay.
What I was getting at was that if someone doesn't care about the lost enough to minister to them with whatever gifts of ministering God has given them, something is terribly wrong with their heart. And sometimes, God asks people to get out of their normal comfort zones and give someone a stern warning, not to judge them, but to warn them that God will, because anything that displaces God in a person's life is idolatry.
If people hadn't done that in my life, I honestly am not sure I would be saved today. Some people are drawn to Christ by His sheer love and healing, but others have to be hit over the head with a brimstone two-by-four, which I most certainly did. Witnessing methods are as varied as individuals, but all are powerful if being led by the Holy Spirit.
The thing about an encounter with Mormon/JW missionaries is that spiritual talk is wide open fair game, a relatively rare opportunity in the Western world. You can broach the subject without seeming rude or pushy at all, and that puts it a lot more into most people's comfort zones than approaching a stranger on the streets would.