How we cite our quotes: (Part.Chapter.Paragraph)
Quote #1
Everyone had always said that John would be a preacher when he grew up, just like his father. It had been said so often that John, without ever thinking about it, had come to believe it himself. Not until the morning of his fourteenth birthday did he really begin to think about it, and by then it was already too late. (1.1.1)
When John turns fourteen, he begins to think about his own feelings about the preordained plan for his life. Part of his growing up has already been planned for him; everyone says he'll be a preacher, and he hasn't questioned it, so there doesn't seem to be another option for him.
Quote #2
Around the time of his fourteenth birthday, with all the pressures of church and home uniting to drive him to the altar, he strove to appear more serious and therefore less conspicuous. (1.1.9)
John is growing up; he's obviously no longer a child at thirteen-going-on-fourteen, and it's not so much that he is getting more mature; it's that everybody expects him to be more mature. In his community, growing up means going "to the altar," or converting and being saved. He knows it's expected of him, so he starts preparing himself.
Quote #3
John watched, watched the faces, and the weightless bodies, and listened to the timeless cries. One day, so everyone said, this Power would possess him; he would sing and cry as they did now, and dance before his King. (1.1.17)
John has been shown, over and over again, examples of what it will be like when he finally comes of age. When "the Power" possesses church members they are overcome, literally filled with a spirit that makes them dance or throws them on the floor. He's seen what he should expect, but it just hasn't happened yet.