Nice to see someone else into Christian karaoke!
I follow the Christian music & Christian karaoke charts pretty closely.
Are you looking for the latest tunes, older music, or something else?
And are you looking for karaoke tracks, or are you looking for tracks in different keys?
With Christian music, there is Christian karaoke, and then there are accompaniment tracks, aka performance tracks, backing tracks, etc. The difference is that many titles listed as accompaniment tracks often come in different keys to accommodate different vocal ranges.
If it's Christian karaoke you're looking for, I would suggest Amazon.com since they have a large selection of songs old and new:
https://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Ddigital-music&field-keywords=Christian+karaoke
The Karaoke Studio sometimes releases a Christian song on CDs, such as Lauren Daigle's "Trust In You" on Greatest Karaoke Pop Hits of the Month (March 2016). You can find their albums on cdbaby.
And of course, if you want older Christian karaoke CDs or CD+Gs, I would do a search on Ebay for Big Fish Karaoke. They're a now defunct company who released several volumes in the 1990s.
lastly, if you're a singer and are looking for accompaniment tracks for yourself, Christwill.com has a large selection and so does Christianbook.com - I visit both and order from them all the time.