Well Obama did at a minimum grow up as a Muslim, until his mother left his father. Here he talks about his early experiences.
https://www.youtube.com/watch?v=tCAffMSWSzY
One part of the video below was cut short. That is the interview with Stephanopoulos. Stephie has to correct him, when Obama refers to himself as a Muslim. A real journalist, would have asked for a clarification. But that is a subject for another time. The thing is that if I asked an atheist, what religion are you, I doubt that he'd inadvertently say "Evangelical", even if he spent the first 5 years of his life as an Evangelical. So this brings up a question of did he make a mistake, or does he not want to reveal something?
So here is a better clip with more interaction between these two.
https://www.youtube.com/watch?v=IKQhkh8xhE0
Another point is that Obama on numerous occasions, maybe more than 100 times, has commented on "Extremists" not being Muslim. Now what is Obama authority on who is and who is not a Muslim? For example, if someone calls themselves a Jew, there are some sects that may not recognize that particular sect as being Jewish. And they can run down a laundry list of why, just as Obama does in the video below. But you don't have Secular Humanists or Christians going around saying that Joe Schwartz is not really Jewish, because they know better what being Jewish is. They have no authority to do so. So again I ask, what is Obama authority to decide who is or is not a Muslim?
https://www.youtube.com/watch?v=pwp8qKvE-0g
Lastly, as to your comment on what people of Islam do, you should realize that many do not follow strict dogma when it comes to diet or customs of attire. Many Jews do not follow the strict restrictions of being kosher. I remember a few years back, Supreme Court Justice Elan Kagan responded to a question on where she was on Christmas Eve. She said, "Probably like most Jews on Christmas Eve, I was having dinner at a Chinese restaurant." The odds of finding a kosher Chinese restaurant are higher than getting hit by lightning. Also I'm sure you remember those pious Islamic terrorist who in 201 blew up the Twin Towers, Pentagon and crashed the jet in Pennsylvania. What were some of them doing prior to going on Jihad? They visited a strip club and were downing drinks. So much for stereotyping people adhering to religious rules.
So we'll see if you are true to your word about my reasoning being welcomed.