For me, reasonable criticism and debate involves a degree of respect and decency, while seeking to refrain from personal attacks. For example, I would disagree with your opinion that Islam promotes regressive attitudes and behaviour, while simultaneously recognising your right to hold that opinion and your right as a human being to not be verbally or physically abused for holding that opinion. If we were to (on a thread about that) be discussing it, I would seek to try to understand where your opinion came from and hopefully be able to share my own perspectives.
Examples of what I think probably shouldn't be normalised as "reasonable criticism" (and should instead be classed as Islamophobia and Anti-Muslim hate) include but are not limited to...
Being spat at in the street.
Being physically assaulted.
Rape threats.
People threatening my living child and being happy about the fact that one of my children is dead.
Death threats.
People refusing to serve me in shops because "we don't serve terrorists".
Discrimination in healthcare.
Discrimination in employment.
Guilt by association, the near-constant absence of the same levels of consideration and empathy that other people are able to expect.
Trying to trick people into eating food that's contrary to their beliefs.
Lack of the respect afforded to other minority groups.
There are many micro-aggressions experienced by Muslim people every day. Every day, the media we see tells us that we are not welcome and not safe here. Every day, people tell us through their words, actions and inaction that we are not welcome and not safe. That's not "reasonable criticism".