This rule of thumb applies fairly broadly in Christian publishing. That is, if you're referring to something in a general sense, you can leave it lowercase—so when mentioning a particular scripture, you would capitalize the term you're using, but when talking about scripture as a whole, it's lowercase.

Do you capitalize Holy Scripture?

Religious Terms

* Bible and Scripture are capitalized, but biblical and scriptural are not. Similarly, capitalize the Almighty but not almighty God.

Should Psalms be capitalized?

Books of the Bible are always capitalized but never italicized. ... 2 Chronicles; Second Chronicles; the second book of the Chronicles. Psalms (but a psalm). Mark; the Gospel according to Mark.