I have seen the hate messages by Hindus and I oppose their language. That doesnt mean that I disagree with the content though. Like you said correctly, we can agree to disagree respectfully.
I personally believe this abusive language is out of frustration. Frustration from the government actions and the media. Not one Muslims acknowledges that Muslim invaders plundered and destroyed temples in India. This is a historical fact. Not something invented by BJP/RSS. I myself have seen the Krishna Temple in Mathura covered by a mosque. Where do you expect the Krishna temple to be in Mathura or Mecca ? Same applies for the Ram temple in Ayodhya.
When Hindus ask that Ram temple be re-built and an alternate land is offered for the Babri masjid, muslims dont accept that either. So BJP makes use if this sentiments for political gain. BJP is not something that came from outside India. It came from within out of the frustration that Hindus felt under congress rule. The fact that BJP is not in power implies that many Hindus still support congress. But more and more bomb blasts by muslim extremists will cause Hindus to move towards BJP.
Did you notice that all the verbal abuse is by educated Hindus which obiously are pro-BJP and anti-congress ? As the education level goes up, this trend will continue and unfortunately we will see more abuse and polarization.