A fellow named Blaise Pascal suggested that people pray to or worship God whether or not they believe in him because if he does exist, they will get rewarded, and if he does not exist and they just die, they are not losing anything. This suggestion was called Pascal's Wager.
In practice, this idea really doesn't work, because since God does exist, he would know if someone is pretending to believe in him.
The only way that serving God works is if people actually put faith in him and obey him because they love and respect him, and want to live in the way that he wants them to live.
As an example of what trying to pretend to worship the true God leads to, at one point certain Jewish religious leaders of Jesus' day made changes in the Law that God gave them so that they did not have to serve him from the heart, but just look like it, They knew that they should honor their father and mother, because this was one of the ten commandments, but they made up a custom called Corban, which means that if a son had money or possessions that their parents might need, he could just say that it is all a gift dedicated to God, so they can't give them to their parents. Jesus said that they honored God with their lips, but their heart is far from him, and it is in vain that they worship him because they teach the commands of men as doctrines. Matthew 15:1-9
So, is saying that one is serving God or joining a church while being an atheist doing the same thing? And would God accept that pretense?
If you want my opinion on which God is best to choose, I would recommend Jehovah God, because he can read your mind, and cannot be fooled. He will know if you are serving him in truth or not, and will judge you honestly according to what you are inside, and your deeds.