Ahok angered religious conservatives after he referenced a verse from the Islamic holy book, Al-Maidah 51 of the Qur’an, rather boldly telling voters they should not be duped by religious leaders using the verse to justify the claim that Muslims should not be led by non-Muslims.
Indonesian hardliners have huge influence, and are responsible for much of the persecution. If he does get convicted he could face 5 years in prison. Thankfully he's not in Pakistan where he could face the death penalty.
More on The Guardian UK.
More info on this France 24 video, including how former president of Indonesia- Susilo Bambang Yudhoyono- has been supporting the hardliners, more than likely because his son is running against Ahok in the upcoming governor elections. Just politics as usual. But it's shameful that Muslim majority countries continue to persecute minority religions, while Western countries continue to embrace Islam.