In the United States, the FTC requires that a material connection — including earning a commission — be disclosed clearly whenever you recommend a product. This is general guidance, not a legal opinion, and other countries have their own rules that may differ.
Something plain and unambiguous, near the recommendation itself: "I earn a commission if your church subscribes through this link." A disclosure buried in a footer, an "about" page, or a link people have to click to find does not satisfy the requirement.
Disclose before the recommendation, not after — a reader deciding whether to trust your opinion needs to know about the commission before forming that trust, not after clicking.
This page is not a substitute for reading the FTC's own published guidance, or for asking your own counsel if you are uncertain how it applies to your specific promotion.