Neither you nor joch have any idea how many professing Christians or Muslims truly believe in their faith. Maybe it's more in one than in the other. Maybe it's not. Joch argues without grounds that Christians follow freely while Muslims are coerced. You argue that the billions (sic) of Muslims are legitimately faithful. How do either of you know that?
I'm not aware of any branches of Christianity where children get full membership regardless of whether they want it. I know of ones where young people have to profess their faith of their own volition (you could argue whether an 8-year-old really understands what he is professing; nevertheless, it is still voluntary). I know of ones where young people must go through confirmation so that they have an understanding of the faith they would be professing. Where is this church to which you refer that is conscripting child members?
Your notion that the psychological pressure of the teaching about somehow is more manipulative than the sharp point of a knife in keeping followers in line does not ring true. People leave the faith of their fathers in this country all the time. The consequences of that here are mild. There are some heavily Roman Catholic countries where the ostracism is worse. But in Muslim countries, families disown apostates, and apostates are subject to death.
One key difference between Islam and Christianity is how they treat the secular world. The Christian Bible makes no claims upon how government or the market or society is to be run, save for the ethical requirements of believers within those venues. (Of course, this differs from the stentorian dictates laid out for Israel in Old Testament. But we aren't professing tabernacle Judaism here). The Koran, on the other hand, lays out exactly how the government, economy, society, and everyday life are supposed to be conducted. So many of the Muslim lands are run as theocracies under Shari'a law. There is no Christian equivalent to Shari'a law.
I would suggest that it is significantly more difficult, having been born into a society where every aspect of life falls under the au es of the dominant religion, to abandon that religion, even if one's doubts about that faith might make practice thereof merely perfunctory, than it is to abandon a majority religion in a secular society with diverse cultural influences.