I have the same problem, I keep quiet when it’s people that I don’t know. “She’s just a judgmental person…she’s schismatic anyway (I’m not, BTW)…” Will they argue back and come up with a point that I can’t argue/defend? Will it do more harm than good? God knows our true motives for why we do what we do, whether it’s pride, cowardice, or prudence? All we can do is pray for discernment, ask for his forgiveness (when the motives aren’t prudence, or in some cases of cowardice, that it is venially sinful, personally). We have people at our church doing things that shoudn’t be done and I don’t say anything about it to them…

…My brother, on the other hand, and his dear age of 17 (now 19 and a Navy man) would speak up in the church when behavior was inappropriate, gently at first, but very firm if it continued. I continue to pray for discernment and strength, to know when to speak up,
or be silent, and to have the strength to follow that inspiration. Continually pray to the Holy Ghost.