Everything. The Shah had manged to systematically discredit and destroy the secular opposition, which had no real social support comparable to the religious leaders, many if whom were longstanding opponents to the Shah and foreign meddling in Iran. Many of the leaders of the secular opposition tried to ride Khomeini's popularity and hoped to edge him out of power later, and failed to do so, so you'll see exile dissidents claim g that Khomeini had "stolen" the revolution, when in fact he always owned it and was it's leader. The arrival of Khomeini from Paris to Tehran and his funeral were among the largest gatherings of humans ever. In contrast, no one even remembers the names of the various hangers-on.