Well, apparently, I've been told by at least 6 people among various forums that I'm irrational for not having complete trust, thus why I am a bit annoyed with this crap.
You are not irrational for not having complete trust. Actually, its rather irrational to completely trust any group 100%.
What is irrational is to distrust a group more than you distrust a similar group simply due to an action perpetrated by a small minority of the first group...an action that is also at times present in those other similar groups as well.
For example, using the example YOU chose to use in your OP, its not irrational to not be fully trusting of all muslims. It is however irrational to distrust Muslims more than Christians, or Jews, or Athiests, because some have killed a lot of people.
Now, because something is irratoinal doesn't mean its not understandable.
Lets say you go to pet a dog and he immedietely bites you. It is irrational to be wary when trying to pet any dog after that because they may bite you, because by and large most dogs are not going to respond by biting you the moment you try to pet them. Its irrational to apply the actions of that one dog to ALL dogs through your actions. However, it is understandable that you are wary in the immediete aftermath because of the trauma of the incident.
It is even MORE irrational if you're wary of petting dogs after that point, but you're not wary when petting cats, snakes, or other pets that can bite.
It is entirely possible for an action to be both understandable and reasonable, while at the same time being illogical and irrational.
Its not irrational that you don't trust Muslims 100%. Its irrational that you distrust all of them to a greater degree because of terrorist attacks. However, due to the traumatic nature of the 9/11 attacks, I would say that such an irrational fear is also an understandable one.