Sure, Facebook changed their algorithm so that people will see more of what Facebook believes they want to see on their wall feed.
This happened. Since promotional material isn't desired by most, they're limiting a lot of Facebook Page content such as YOUR content. But, seriously, I don't think that's the issue (although we should all be cautious about all the promotion we put on our Facebook page).
However, maybe there's a better reason why you're getting very little engagement on your page. If you don't have a lot of followers, don't have a lot of post likes, and certainly don't get a lot of post shares, then maybe, just maybe you have these 3 problems:
1. You're not asking your congregation.
Don't assume that people in your congregation will automatically follow your social channels. Continuously remind them of the benefits of following (i.e. extend the church message through the week, see fun videos that teach spiritual truths, see outreach pictures of how you're reaching the community, etc.). Then remind them to like and share your posts to their wall. But make sure your posts are worth of it! Promotional posts aren't.
2. Your content isn't all that interesting.
Know your audience and what interests them. Search through some of their Facebook walls and see what they share and like. Then consider how you can contribute posts that are similar (using your church brand and message). Also, review your past posts to see what has interested your current followers (based on how many shares and likes are there), and then do more like them! Many churches continue to post content that gets little or no engagement and expects to gain followers. Stop the insanity.
3. The entertainment value of your posts is lackluster.
Entertainment isn't frivolous. Entertainment is simply helping your followers spend time so they receive perceived value. Making them smile, nod, cry, or say "awwww" is entertainment. Social media is an entertainment channel! People look at their Facebook walls when they want to fill time much like turning the TV on. Give them good entertainment and they'll keep coming back. They'll also tell their friends about your "show" and you'll continuously add to your page's followers.
PLEASE NOTE: without engaged followers on your Facebook page, there is no purpose in investing time into it.
Get your content right, so that you're good stewards of the channel that God has given you. Once you have the followers, OCCASIONALLY, remind them of ministries and events that are coming up.
But make them feel like an entertaining TV commercial that interrupts their favorite show. Then return to your regularly scheduled broadcast.