It is our believe as christians that there is only one God who made the heavens and the earth. He is one that by Him we move and have our being. Knowing God is a personal experience. It is should not be based on what we have heard others say.
Knowing God is an experience that is personal. It is our relationship with God that truly defines us as Christians. However, it is not everyone that has the same beliefs. Different people emerge from different backgrounds and may have different forms of worship.
But according to what the bible tells us we are aware that God has made Himself known through His son Jesus Christ. Jesus came down to earth to make us understand who God truly is and to establish a relationship between us and God. So that those serving the wrong God would turn around to the one true living God.