Find an agent. There are several standard listings of agents, including the Guide to Literary Agents, that are divided by genre and provide tips to land the right agent for you. Because Christian publishing is a niche market, publishing only 5,900 titles each year (mostly nonfiction or children's titles), it is even more imperative to have an agent. Agents know what the publishing companies are looking for, and can help you attract the right publisher. An agent will also help get your manuscript in the door of larger publishers, who usually do not accept unsolicited manuscripts from writers without representation.
Write a query and send it to the Christian publishers your agent has decided are most likely to publish your book. Although your agent will help you craft your query, you should be available to assist in any way requested. After all, it is your book. You should be able to give a one paragraph synopsis of your book, and write a biography of yourself to help your agent place your book with several potential publishers.
Send the potential publisher your book proposal only after she has requested it. In addition to a sample chapter of your book, the proposal should include details on your target audience, or who will most likely buy your book and where they will purchase it (Christian bookstores and websites, churches, Christian music festivals, etc.). It should also include a detailed author platform, explaining who you are, detailing your social network presence, including links to previously published articles and chronicling any of your media or speaking engagements.
Send in your completed manuscript when requested. Your agent will have already aided you in making your manuscript more marketable, which will greatly increase your chances of having your book accepted. The acquisitions editor will read the entire manuscript and decide if he will forward it to the publisher's editorial committee and publishing board for final acceptance.
Work with your agent to negotiate a fair contract upon acceptance of your manuscript by the Christian publisher. Your agent will work with you on your rights -- such as foreign, film and electronic --- as well as help you negotiate your advance. You may also be able to negotiate a multi-book deal at this stage. Negotiation can be a lengthy process, but it is well worth it if it generates the best possible deal for all involved.