There do exist discerning elements in geometry and form used in architecture by Islamic groups and Christian groups.
Compare the architecture of Spain under Islamic control vs Christian control.
Compare Alhambra in Granada Spain as a type of Islamic Architecture. (Alhambra is actually a good example of Islamic, Jewish and Christian architecture. The original construction circa 1100AD was Islamic, later added with the Jewish influenced Lion's Palace (12 lions representing the 12 tribes of Israel), and later added the Carlos V Palace by a Christian Monarch Carlos V beginning circa 1527 and completed in 1957.
Compare this to later 16th century architecture of northern Italy and the Church.
San Apollinare
http://www.skyscrapercity.com/showthread.php?t=839410&page=6
Alhambra
http://www.alhambra.org/eng/index.asp?secc=/alhambra/alhambras_guide/carlos_v_palace
It’s probably as disingenuous to criticize ‘Islamic Art’ as not being a true form of art as making a similar criticism of “Christian Art”.
Alhambra and the Taj Mahal are beautiful works of both art and architecture no matter who designed, influenced or built them. Id like to one day see both in person. The mosaic tile work, which is Islamic, is the most impressive to me. And some of the textiles, rugs for instance that came from Islamic countries are truly works of art in and of themselves. But I also love many of the textiles that come from India.
Not long ago I passed by a very attractive Indian woman wearing a traditional sari that was indescribably beautiful. The deep and rich colors, the finely detailed embroidery and bead work and the way the differently weighted fabrics were draped and flowed; it was absolutely beautiful and very feminine and I couldnt help thinking how much Id like to wear something like that no, not every day but on a special occasion, I think I would feel beautiful wearing that. Id also love to be able to afford a really good oriental rug, i.e. such as those once made in Iran or Turkey one day; Id have no problem having one in my home.