You're assuming that becoming a devout Christian is the only possible conversion possible. It's not. Matter of fact, it's far more likely that she has been genuinely converted to the areligious American norm.
Now by that I mean the reality of America today. Folks might say they're Christians or Jews, or whatever, every time gallup does a poll, but the truth is that most of them are out on Saturday night communing with Jose and Jack. Movies, TV, X-Box, nightclubs et al get more face time with the average American than anything even remotely spiritual.
You're assuming that becoming a devout Christian is the only possible conversion possible.
The only power that exists which can break the power of Satan and his evil and lies and bondage in Islam is a power greater than Satan.
And that power which is greater than Satan, is the one who created all things in this world and universe -- the God of Abraham, Isaac and David.
Another "false idealogy" doesn't have power to break the bondage of Satan and his lies and corruption.
So, yes, it's only the God of Abraham, Isaac and Jacob who has that ability to break Satan's power over an individual. The Bible also makes that clear that all are in bondage to the power of sin and Satan, until God acts on one's behalf to be able to break that bondage, by His power and the Holy Spirit (and that is done by the person asking God for His salvation and thus, His help in that salvation that He offers to all).