THE pedestrian bridge on Jalan Sudirman, in the heart of Jakarta, is certainly not the siratalmustaqim, the holy bridge Muslims believe leads to heaven. But a Shari’a bank advertisement stretching the length of the bridge might disturb the public. It reads, “Leave the ways of usury, take the halal road”.

The ad is eye-catching. It exhorts people—in this case, Muslims—to stay away from conventional banking that applies usury, to happine