Lion King, Every Christian believes in one God. The problem with this whole discussion is to understand what the word "one" means. Concerning "One God,"
The word, "One," can be,
Single in number, as an individual, meaning one man, one book. But, it also can mean, one in union, or, one united body.
The word one, like many other adjectives is used without a noun, and is to be considered as a substitute for some noun understood. For example, if we say,
1. "Let the men (plural) depart one by one (singular)."
2. "Count them = (the men plural) one by one (singular.)"
3. "Every one = (speaking of a group of men) has his (singular) peculiar habits."
Gen.2:24, "Therefore shall a man leave his father and his mother, and shall cleave = (be joined) unto his wife: and they (plural) shall be one (singular) flesh." Two people, one flesh.
Gen.34:16, "Then will we give our daughters unto you, and we will take your daughters to us, and we (plural) will dwell with you, and we will become one (singular) people." That is, many people will become one people.
Col.3:15, "Ye = (many) are called in one body;" In this verse we see that many people are called into one body, which is the church of Jesus Christ.
When we speak of One God, we are speaking of the Father, Son, and Holy Spirit, as being one in union. Union implying two or more being united, a conjunction of minds, wills, affections, and interests.
I hope this clears up your understanding on the subject.
Phil LaSpino