"Europe has denied its Christian roots from which it has risen and which could give it the strength to fend off the danger that it will be conquered by Muslims -- which is actually happening gradually," Vlk said.
"If Europe doesn't change its relation to its own roots, it will be islamized," the 77-year-old cardinal, who was named Prague archbishop by pope John Paul II in 1991, added on his website www.kardinal.cz.
He blamed immigration and Muslims' high birth rate for helping Muslims to "easily fill the vacant space created as Europeans systematically empty the Christian content of their lives".
"At the end of the Middle Ages and in the early modern age, Islam failed to conquer Europe with arms. The Christians beat them then," Vlk said.
"Today, when the fighting is done with spiritual weapons which Europe lacks while Muslims are perfectly armed, the fall of Europe is looming," added the cardinal.