What is the basis for Islamic design?

1.) Early Islam is unique in the fact that it combines traditional art values from Eastern and Western civilizations (From the Classical Romans/Greeks to Byzantium to Persia). So I would say that the basis would be Influence from traditions to make into their own. Organic and geometric designs also come into play as they tend to cover every inch of a surface with some sort of pattern, plain or complex.

It sounds like it doesn't make sense, but Islamic art was actually originally and dominantly secular in its early stages. Subject matter (yes, there actually was a lot of it) generally focused around the Dionysian scenes of leisure, wealth, and happiness (from the Greeks/Romans). This is seen in the palaces for the most part. Or, there will be portraiture-like scenes that are very flat-looking and reflect Byzantine style art.

2) Again, it differs in the fact that Christian art is, well, religious based. Islamic wasn't necessarily...at least, at first. Also, Christian imagery allowed the depiction of Holy people where the later style of Islamic art got rid of figuration in general. If The Prophet was depicted, he would be without a face, or "censored" I guess you could say. Eventually the rich designs of leisure and wealth that they had before slowly turned into Non-figurative art. In time, it turned into dominantly geometrical and organic designs (like scrolls and vines)

3.) A lot of mosques were actually converted from ancient churches. Take the Mosque at Cordoba, for instance, which before being a Christian church was a temple to Jupiter. Or Hagia Sophia. Point is, the Muslims borrowed a lot of style from the ancients, but also added their own features. Like a church's Pulpit, the Mosque will have a Minbar. A priest is like an imam. Like an apse with an altar, the mosque will have the mihrab with the Qibla to focus prayer onto. A mosque area of prayer is lined with columns in an open space while the area of prayer in a church consists of the nave, narthex, and transcept.

The phrase "Islamic art" is an umbrella term for post-7th century visual arts, created by Muslim and non-Muslim artists within the territories occupied by the people and cultures of Islam.Islamic artists habitually employed flowers and trees as decorative motifs for the embellishment of cloth, objects, personal items and buildings. Their designs were inspired by international as well as local techniques. The difference between christan art and islamic art is that christan art is of human objects while islamic art portrays the meaning and reflection of things.Similarly, there are themes and types of objects that link the arts of the Islamic World together. Calligraphy is a very important art form in the Islamic World. Through its brilliant use of color and its superb balance between design and form, Islamic art creates an immediate visual impact. The designs of mosque and chruch are different because each structure is designed and built for the purposes of practicing a particular faith.

hi , i will try to help u but if i am correct please chose me the bist answer u may found ur answer in this link http://scholar.google.com.eg/scholar?q=What+is+the... 

good bye with best wishes