Why are there many religions about the same God?

In addition to what Will said, although there are religions about the same God, there are those who have different views about the teachings. Take Protestantism for instance. It is a branch of Christianity separated from Catholicism and the Catholic Church, they did not believe in the authority of the Pope. Protestantism began as a movement to reform the church and from there a new, separated branch of Christianity was born.

There is an idea called universalism which is the belief that all religions worship the same God; God is just know by different names. Universalism is not true and it is not Christianity. Man is looking for something to satisfy them and it is a relaltionship with God that they need. Only Christianity worships the one true God and the other religions do not worship the same God, but a false God even if they claim to worship the one and only true God.

How do you know you worship the one true god if each religion says they worship the true god or gods

Baha’i take this a step farther. Baha’i believe that God has had many messengers, Abraham, Moses, Krishna, Zoroaster, The Buddha, Jesus, Muhammad etc and that each messenger presented teachings appropriate for that particular time and place.

The idea of God is humans trying to make sense of the aura of the observable world. Every culture has some religion to try to make sense of the world. More powerful religions have eliminated others not so powerful since ancient times. The religion that is true is largely relative and based on your geographical location as well as your upbringing. Whether all different religions are worshipping same God is hard to say but clearly they are all worshipping the one they believe created the world but with different interpretations.