A Or a Z

I'm searching for the reasons of the seasons, but can only find small elation of mortals equation. Is it the truth they've formulated? Not of how one cloud is made or what causes shade, but the essence of the sum. Is it the One who caused B.C. to become A.D.? Yes, I have paused and considered that belief. But I forward and tearful found little relief and grew rather fearful. For I could not hold amorous sensation and believing salvation in this fleshly mold. Why must it be so? I really don't know why we must choose to be a believing A or a believing Z. But either way we must believe something.