Not exactly true. I know people who are from Muslim culture but they like dogs, drink beer, pretty normal although maybe don't eat pork. You can say they are "not Muslim" but their distance from the tenets of the religion is not different than the distance of many Christians from the tenets of Christianity.
And these kinds of people are not the terrorists, ever.
It is not about following taboos such as refraining from pork or alcohol. I was replying to the user who was referring to Muslims who don't believe in god (Allah). Those who drink alcohol and eat pork can be Muslims. But those who don't believe in Allah can never be Muslims.