Simply put, it would be a lie for me to give such capitalizations. The capitalization of these words is based on the concept of worship for the biblical god. For me to capitalize those words would be an implicit statement that I thought the biblical god worthy of such worship. I do not. And, please, let's leave behind the excuses for why it would be "grammatically necessary" to capitalize those words. The word "he" does not become a proper noun just because it refers to your preferred god. I am not being disrespectful if I treat your god the way I (and you) treat all others.
The purpose of language is communication. My refusal to capitalize a word that does not warrant capitalization (despite a long tradition of an improper capitalization) does not impede communication -- aside from your taking an unwarranted offense. Randomly capitalizing letters in the middle of words does impede communication. The brain gets stuck because it expects the capital letters to be at the beginning of words or (for emphasis) fully capitalized throughout a word. And yet christians like to make that false analogy. Grammar rules reflect the way people write and speak, not the other way around. Customs and traditions ultimately have a source. And, when I must reject the source, I also reject the tradition. The source of capitalizing words that refer back to your god (as most nouns and adjectives identifying a religion do) is a desire to enforce special honor for your god. Your god warrants no special honor. I would be engaging in an implicit lie if I were to "go along to get along." I can't do it, not in good conscience.