I have a book I like to use called"Charts of Cults,Sects,and Religious Movements"By H.Wayne House.I would also recommend looking at others holy texts for yourself.If you are firm in your faith but wish to better understand others,studying their beliefs will be helpful in understanding them.What I have found is that very seldom do you find any religious belief system to completely agree within itself,Christians dont always agree with Christians,Buddist dont always agree with Buddist,Muslims dont always agree with Muslims,and the list goes on and on.You will have radicals on both ends of every faith.