(Turkish classical pianist Fazil Say performs during a concert in Ankara October 14, 2010. REUTERS/Stringer)

Turkish concert pianist Fazil Say’s exuberance has won him fans around the world, but it has also helped land him in court as a cause célèbre for those alarmed by Turkey’s creeping Islamic conservatism.

On trial for insulting religion in citing a thousand-year-old poem on his Twitter account, the 42-year-old performer and composer told a first brief hearing in Istanbul on Thursday that he denied the charge, which can carry an 18-month sentence.

As fellow artists crammed the courthouse in a show of support for Say, who performs with some of the world’s leading orchestras, the case was adjourned for four months.

It was a retweet sent in April of a verse in which the 11th-century Persian poet Omar Khayyam mocks pious hypocrisy which led prosecutors to charge Say with “explicitly insulting religious values”. Religious conservatives have become ever more assertive since Prime Minister Tayyip Erdogan’s AK Party, which has roots in Islamist politics, swept to power a decade ago.