By Emily Rauhala December 23, 2015 Pastor Su Tianfu, a Protestant preacher from Guiyang, China, reads the Bible on his iPhone. His church was recently shuttered in a sweeping government crackdown. (Emily Rauhala/The Post) GUIYANG, China — Pastor Su Tianfu slides into the back seat and tells the driver to hit it. He looks over his shoulder: “Is there anybody following…