This is an assertion which is either true or false. You assert it as true.

Correct. I want to point out what this is an assertion about: it is about the meaning of the word 'morals'. I.e. a definition, not a statement of logical or physical fact.

If you think that "there are objective morals" that is a different claim about the meaning of the word, but also (and much more importantly) a claim about the existence of something - and I'm asking you to define that something. Let's leave aside for now the issue of why you call this something "morals", let's taboo that word. Please describe this objectively existing something you are talking about.

There are plenty of people who do believe there is an objective moral truth.

I don't even know if this is evidence for or against them being right. There are plenty of people who are very wrong about lots of things that are not part of their everyday lives.

You can read about it in wikipedia and in the Standford Encyclopedia of Philosophy.

I have now read both articles. (You linked to Stanford twice, so I read the WP article "Moral Realism".)

Wikipedia doesn't give a single argument for moral realism, it just says that if we accept it, that makes it convenient to reason about morals. Which is not evidence.

The Stanford article lists many arguments against realism, but no arguments for it. It seems to conclude that because realism arises from "common sense and initial appearances" [I disagree strongly] and because they identify problems with some alternatives, realism should not be dismissed. Yet they identify no problems with my approach; and even if they did find problems with all known other approaches, as long as there is no problem to be found with the rejection of realism in itself, then there is no valid reason to accept realism.

To sum up: moral realism claims truth-properties for moral statements, but it also claims they cannot be evaluated for truth on the basis of any observations of the physical objective universe. That reduces it to the statement "our common sense tells us so, you can't prove us wrong, we don't have to prove ourselves right". Not very great philosophy.

By this I take it to mean you would like to define "it is wrong" and "it is right" to mean "most people think it is wrong" and "most people think it is right." I find a lot of problems with that definition.

No I don't want to define it so. It can and does mean different things in different contexts. Whenever there is doubt we should make it explicit what we mean.

Whether I understand moral realists is a separate issue. First I would like to understand moral realism itself. Please taboo "something is right" and tell me what your claim of objective moral truths or moral realism means.

What do you do about me? Incarcerate me while telling me that I am being imprisoned for life not because I did or want to do something wrong but because "most people think I did something wrong?"

I don't like incarceration itself, but it might be the best alternative available. Regardless of what I do with you, it would be because "most people (including me) think you did something wrong", not because "it is somehow objectively wrong".

I do ask you what YOU think. Do you think I am wrong to kill these children?

Yes I do.

How much does it matter that I disagree with you?

It matters for some purposes. For instance, if there were reliable ways to check and modify a person's actual moral feelings, I would want to impose on you modifications that would make you view killing children as immoral. I would prefer that to incarcerating you.

Another possible difference is in the severity of punishment, if any. One goal of punishment is deterring other potential criminals (and your own potential recidivism). People who don't have moral feelings stopping them from killing children, might need more punishment (ceteris paribus) to achieve the same deterrence. So it might make sense to punish you more severly, to influence people like you who don't share the social morals being enforced to follow them anyway out of self-interest.

Also, your lack of these moral feeling makes you likely to kill children again in the future (as you noted yourself), so I would want to incarcerate you for longer so as to protect children from you for longer.

If it doesn't matter that I disagree with you, doesn't that mean that you think it is objectively wrong?

As I said, it does matter. But suppose it didn't matter: suppose I sentenced you without regard to your moral feelings. That wouldn't mean I thought your behavior was "objectively wrong". It would simply mean I was sentencing according to the moral beliefs of myself (and, by stipulation, most people). I see nothing wrong in doing so. To refrain from doing so would be to refrain from acting according to my moral beliefs.

I think some confronting this might want to say there was something wrong with me if I liked killing children and didn't feel there was something wrong with it.

"There is something wrong with you" is yet another different, confusing, usage of the word 'wrong' in this discussion :-) Tabooing 'wrong' it means simply: you are unusual in this regard. Which is true by stipulation of our scenario - as you said, "most people think you did something wrong". Anything else ("who is human?") is arguing about the definitions of words and is not interesting or relevant.

I do think there are powerful reasons to think morality is objective

So tell me what they are already!