Are some opinions more valid than others?

Many people, including my boyfriend, have told me that everyone has an opinion, and nobody is ever "right" or "wrong" in their opinion on something. But is that accurate? I often tell those people that opinions are personal evaluations of things in reality, based on the facts that one has identified. Your opinion might be that Islam is a religion of peace, for example. I would disagree, because the Koran explicitly promotes the killing of non-believers (among many others), and many Islamic terrorists cite Islam as their motivation for performing acts of terror. My opinion is based on concrete facts that I have identified; I think it is valid and substantiated. I also think the opinion that Islam is a religion of peace requires substantiation that can't be given. You might say that there exist many peaceful Muslims, and you would be right, but that doesn't change the fact that there are dozens and dozens of passages in the Koran that explicitly promote violence. Is one opinion more valid than the other, or are they equally valid? Is one opinion a better evaluation of facts than another, or are all opinions merely subjective feelings about particular subjects with no basis in reality? Would it be proper to tell someone that you recognize their opinion, but that their opinion is wrong, so long as you could substantiate your statement?