You don't have to love each other, but you have to respect each other.And just as we do not need to agree with each other on many things, we need to respect each others' opinions and differences.
Another thing I feel directly related to this is freedom of speech. Everyone has the right to express their point of view. We may not agree with that opinion, but we should be willing to at least listen.
However there is a thin line between freedom of expression and showing disrespect. The problem is that this line is not concrete, and what may be freedom of expression to some, may be regarded as disrespect and wrong doing to others.
My own "line" is much closer to freedom of expression. But for many people, their line is much closer to disrespect and they see anything and anybody that disagrees with them as completely wrong.
Do you see any line? Do you have your own limits?