Let's think about this for a second: is a religious faith an inherited trait, along the lines of skin or eye color? Is there a "religion organ" in the body that somehow stores the religious genetic code that is passed from father to son? Of course not!
Here is an example: Mary (who is a non-denominational Christian) has a relationship with Abdullah (a Muslim from France) and she becomes pregnant. Abdullah, after discovering this fact, runs for the hills. Mary then meets another man, Fred, who is a Born Again Christian. They are married and Mary gives birth to a son, Barry. Mary and Fred raise Barry as a devote Born Again Christian who attends the local Pentecostal church. The question is this: is Barry "secretly" a Muslim, or is he a Christian? I think any rational person would answer "Christian", unless of course Barry ends up becoming a politician that others disagree with (then all logic gets thrown out the window).
The only counter argument here is that "Muslim" is as much a culture as it is a religious faith. That argument falls flat on its face for two reasons:
- The very word culture implies a set of behaviors and beliefs (see definition HERE) that are shared across a group. I can tell you that, for example, the behaviors and beliefs of a Muslim in Saudi Arabia are different than the behaviors and beliefs of a Muslim in Iran or a Muslim in Indonesia.
- Being a Muslim means, by very definition, that you are an adherent to Islam. Just ask Muslims (citation HERE) themselves. If you are not an adherent to Islam, you are not considered to be a Muslim.