Hey NC!
No, I am not taking the view that strongly expressing a different or opposite opinion is not allowed, invalid, or abusive. I often have and express strong and opposite views myself.
Like you, I too would term the use of expletives (swearwords) as abusive. Some personal attacks, rudeness, and denigrating the person may at times fall into the category of abusive too I guess, depending on the spirit/tone/intent.
As a believer, and as a fellow human, I view the abuse you were subjected to as inappropriate (to say the least).
Causing offense, I would think, can be a very different matter to being abusive. I guess we all do that inadvertently at times. I guess we all can be more sensitive to others' feelings and views.