Well, there is only one God, with capital G, meaning almighy God, but there are

many gods. Jesus made it clear to us in John 10:34-35. He quoted from Psalms "You are gods", and he explained that those who get the word of God are gods. That means we Christians are gods. Another example is Ex. 7:1, where God himself says to Moses "I have made you a god to Pharaoh". So Moses too was a god. Of course we are not some immortal supernatural gods, but we are gods because we have the word of God. There is also an evil God, Satan is called god of this world in 2 Cor. 4:4. So there are many gods, but only one almighty God. So in that sense there is only one God.
In John 1:1 it is grammatically good to translate it "and the Word was a god". You say Greek says God was word, but you have to understand that Greek has a different word order than English. In English the subject has to precede the predicate, but in Greek it can follow. And here theos has no article, so it is good to translate it 'a god'. But we cannot know for sure what was meant, because we are not supposed to know.