Islam is no more a mystery than Christianity. Both faiths have been maligned by men who thought they knew the true nature of God and both launched wars based on that "conceived" understaning.
The problem is not whether which faith is true but rather which faith does the most to promote individual freedom while reinforcing the ideals of the selected ideology.
In that respect, they've both failed.
The more important question is: are you willing to have your faith ascend to a position of dominance over the other based on your supposed understanding of its true nature that hasn't been displayed?
Better to have the role of faith retained to hearts and minds and keep them out of the political arena while the role of government is kept at the minimum of its bounds. Namely giving individuals the opportunity to pick a faith without fear of reprisal.
What you describe is a transient state. Such a state will not exist for any considerable period of time. We need to accept that fact that ALL people have a worldview--some are wrapped in the form of religion such a Christianity or Islam, others in philosophies such as secular humanism (which some even consider a religion), and ALL adherents of a worldview compete for followers who, no matter what the people of a particular world view say about just wanting to "live and let live", move in to positions of control when their numbers are there.
Idealism is often great on paper, but, as with communism, can be miserably applied to reality. Rather than trying to maintain the current transient status (i.e. from a Christian worldview to ???) in vain, we're better off finding and promoting the superior worldview--which, personally, I believe is the Christian-influenced government with which America started.
You have a point. America should never have been founded. Let's petetion England to be readmitted as a colony. I'll go find the Queen's home phone number.