No one will listen to Reverend Jameson as he cautions acquiescence in the face of racial oppression. Far from doing so out of deeply-held religious convictions, this supposed man of God is simply acting out of fear and self-preservation. The old men don't respect him because they resent him for his cowardice and lack of firm resolve. He clearly isn't on their side, and is prepared to allow a blatant injustice to take place in his parish.
One would've thought that Jameson would stand with his community in the challenge they face. But no, he's thinking only of himself, and the members of his flock will never forgive him for it.
Organized religion has often been used throughout history to legitimize all manner of social evils. And the Reverend Jameson's timidity and lack of spiritual leadership is part of this long, ignoble tradition. His moral inertia bolsters the prevailing system of racial oppression, whether he intends this or not. In making a man of the cloth such a yellow-belly, Gaines is drawing attention to the impotence of formal religion in situations of acute tension, where resolute action, sometimes involving violence, is an absolute necessity.