Tap into Christian dating web sites. See if you can get in there and (slowly - trickle type method) start injecting info about your app and links to it as you build up profiles on them. Also look around for Christian forums. There's tonnes of them. Build profiles on them (you could speed this part up if you have or get one of the apps that can automate building forum profiles). Then start maturing those profiles until you can add a signature with a link to your app. In all this, use your social media presence and "other people" on those sites (accounts you control) to create an echo chamber of legitimate sounding profiles who happen to subtly reiterate the wonderfulness of your app. Be a bit subtle about all this and, over a bit of time, you can grow a lot of backlinks and exposure for your app.