Why would Christians believe only "good" Christan will make it too heaven?

This was about two years ago when Fred Phelps came to our school because we did the Laramie Project" and it brought up a lot of debate and heated tensions inside the school. I had a partner for theater and we got into that discussion. She was like " If you don't accept Jesus Christ no matter who you are you will go to hell" I asked her what about Muslims,Hindus,Jewish people? She said "They will go to hell to because you have to accept Jesus Christ" Then she pulls out her bible and shows me a verse. It was weird to me because I grew up with a religions mom and she has the bible memorized and figured out to the end so if I am ever confused I go to her. We even stopped going to church because so many people wouldn't do right and they would want us to tithe out money for the most ridiculous things and they had like "popular" groups in the church. I am a Christan and how dare others say that? If that was true hell is going to be the fullest place in the universe! Ive met sweet respectable people of all beliefs and just because they don't believe in Jesus their going to hell?