Religion and Different Christian Groups

Why some "Christian" groups are not considered Christian by some people...
Many religious groups are considered not as religious as others by people in different sects and denominations. There are many different reasons why this can happen. The main reasons I believe are where the groups get their religious foundation, to show the validity of one's own belief, and because of man's instinct of "I'm right, and you're wrong".
Sometimes there are solid reasons why a group of believers are not considered Christian. …