How do we tell the people about Allah?

First and foremost is that Allah and God or not the same. And if they say “you don't worship the same God we worship,” you say “maybe you are right.”

The word “god” is brand new, it's not even 900 years old and it's not the word used by most Christians in the world, most Christians in the world use the word "Dios," because most of them are Spanish speakers. There's a whole lot more of Spanish speaking Christians than they are English speakers. Sorry, but true. There are a lot of Europeans who don't say “God,” there are a lot of French people (Christian) who don't say “God.” But every single Muslim on the earth is unified in saying "Allah" when we speak of "The One above."

But I've got news for you: There are also several million Christian Arabs who also say "Allah.” And there are many Jewish Arabs who also say "Allah." There are more humans on earth using the word “Allah” to represent the God, and it's the oldest word and it's a form of it in Jehovah (or Yahweh), it's a form of it in the word Elohim or Allahumma. It's a form of it in the New Testament, “Eli Eli Lama Sabachthani?” It's the word that's the basis for the Old Testament and the New Testament in talking about the one true God - "Allah."

And it means the only one worthy to be worshipped and it can't be made plural and has no gender, neither male nor female. So, it perfectly describes the God of Abraham and Mosses and Jesus and Muhammad (Peace be upon them all).