The theology that a person holds often greatly impacts that person's view and actions in life, and this leads some people to feel a justification to always correct a person for any minor theological differences. They'll confront perfect strangers to, as they would say, stand for the truth. They view this as loving, because they think that if the person only holds that view then that person's life would be so much better.
But the great flaw in that is it rejects the fundamentals of how relationships work, or how to get to know and help people works--of how to be loving. If you tell a stranger, or someone you haven't truly tried to get to know or know their viewpoint well, that you think they are terribly wrong on something, what would you expect? All that is communicated there is that one person has wanted to skip the part of getting to know someone and has jumped into telling that person what to do.
Relationships shouldn't be about trying to correct another person or force them to be a certain way. It's about getting to know and appreciate them, and possibly at certain moments--very rare moments, most likely when they ask for advice--that's mostly when a relationship can include this aim to help another see and possibly adopt your viewpoint.
I wonder if some people think the whole world is an academic classroom. There truly should be a difference here and there. In debate class, you debate. In real life, you talk and get to know each other.
Another flaw is that it may be pride, and not love that motivates people. If you see that people don't often like to be corrected on every little detail that you may view as wrong, you'll know that the end result is often they will want to move farther away from you. So what was the whole point? In the end, it may be that the person wanting to correct the other just wants to be and feel right. That's pride and not love. Or at least pride was the main motivating factor, whether the person realizes it or not.
The Bible talks about matters of indifference. We really shouldn't let matters of indifference get in the way of enjoying being brothers and sisters in Christ. People are learning theology over time, and as long as they understand the very foundation of the Bible, the gospel and all it offers to us, then they will be fine. Don't rush, and wait for them to ask the questions.
As Christians, we should be known for our love. Not for a constant fighting spirit over theological differences.
Theology does affect people greatly. But we have to realize our limitations and how human relationships work, and that pride is all too present and common.