Gnostic: Since you are more open minded to discussion. Can I ask why there are so many branches in Christianity?
Because the book they're all based on is incredibly vague and full of metaphors and analogies, and it's remarkably easy to turn it into a gloried Rorschach test that supports just about anything you already believe. Add on top of that the all-too-human tendency to disagree on details and two thousand years of trying to read the same book in different ways and it was really an inevitability that there'd be a million different branches.
Gnostic: How can you be sure you are following the correct teaching in Christianity?
Is there even such a thing? Plenty of people have their reasons for believing that their flavor of belief is the most right, but I tend to subscribe to the idea that all branches are a little right and a lot wrong about a lot of things. Most agree on basic things like compassion and other broad strokes like that, which is something I can get behind, but I don't think anyone's ever come up with a flawless interpretation because of the corruption that typically follows anything too formal. Some churches are little more than popularity contests, and I've even seen a pastor finish a sermon, then beat his kid in the parking lot immediately afterward.
If you're a decent human being, then I'd say you're doing well enough regardless of which details you subscribe to. There are no guarantees when it comes to religion, so you can't really judge anyone's wrongness or rightness beyond that.
Gnostic: What should be the correct perception of Christianity?
Whichever one is being nicest at the moment, I suppose.