I have a good bit of experience with Muslim people, though none of it in predominantly Muslim nations (yet), so I defer to your greater experience. I am concerned not only about Muslim hearts of stone, but about Christian hearts of stone too, which is why I emphasize our need for good works and love.
In the long run, what I hope we overcome is not Muslims themselves, but sin and the systems (principalities and powers) that enfranchise sin … systems that are clearly active in the Muslim world and – though perhaps in subtler forms … in our world too. Those systems oppress everyone they touch, and I believe the gospel of Jesus is the power of God to set us free, and I’m sure you agree.