You're by definition using inductive reasoning. You could not have possibly studied every other belief system present across all mankind..
And you've ironically chosen the religion which happens to be the majority where you were born and live, much as people have done since the beginning of time. Geography is the number one indication as to what belief system you have.
Au contraire. One need not, for example, follow every single belief system that is polytheist to know that it is wrong by virtue of there being only one God. Therefore, it’s been narrowed down to possibly 3 belief systems. Of those, 1 pretty much contradicts the other 2, so that narrows the possibilities even more, doesn’t it...