Let's use a logical diagram here, shall we?
All Christians are religiously intolerant.
Some Christians are religiously intolerant.
The entire diagram (rectangle) consists of all people, labelled "U".
The yellow circle labelled "C" represents all Christians.
The orange circle labelled "R" represents all religiously intolerant people.
The first statement above is obviously false, considering there is some point in the yellow circle that is not a part of the orange circle--if the yellow circle were inside the orange, circle, then C-->R, and you might be justified in saying that all Christians are religiously ignorant. But that's only the case if you suggest that all Christians are religiously intolerant. But that's obviously not what the generalizer refers to.
The second statement suggests that there is some point (ie, the dot between the two circles) where Christians are religiously intolerant (ie, in both C and R) that is true, but this need not be the case. There is also some point in C that is not in R. This most likely is the diagram generalizers refer to. When you say some (I guess most applies here too, as long as you don't say "all") "A" are "B", there is at least one A that is B, but it does not mean that there is an A that isn't B.
So what's wrong with that generalization, if generalizers refer to the diagram above, and not C-->R?
There is nothing wrong with that generalization. I was over-reacting to generalizations in general. What I mean to be upset about is that some people seem to be making conclusions about all
people based on a narrowly defined group of Christians, which is an over generalization and illogical.