Why not? If you believe that people are going to go to hell forever, shouldn’t you be up in arms about warning them?
Some people try that. It doesn’t work long term. I could explain about the parable of the sower and how not all seed finds good soil. Plus, I am not extroverted or outgoing enough to put myself out there to random people.
Everyone should understand the argument that sending otherwise decent people to an eternity in suffering for simply not believing in the right religion (especially if they didn’t even know about Christianity’s existence) is a despicable act. You’re right that such evil actions wouldn’t necessarily disprove the existence of God, though it surely would make him far more villainous than any of humanity’s most evil of men if such a God did exist.
Jesus says if his disciples kept quiet, the very rocks would cry out.
And when you say it is villainous, you color it with your perceptions, with concepts and motivations that may not be accurate to reality.
And this is why I’m not really keen on the conversation. Debate to be had is likely not logical because the logic used might be subject to faulty premise.