For the most part, math is math and a Christian curriculum teaches the same math as a secular one. The differences are in approach….The New Math, Mastery, Spiral.
A Beka, BJU, Rod and Staff….those are traditional and designed for a classroom so they require more teacher involvement (and are Christian publishers.) They are all rigorous, but I don’t know that R&S has a true pre-algebra program.
ACE and Christian Light Education are designed for more independent work and are less teacher intensive. They are have 10-12 workbooks per grade. ACE has memory verses in it and I think CLE might, too. ACE is a mastery program and CLE is a spiral.
Master Books is supposed to be CM. Imo, Math U See is more so. My kids actually mastered concepts with Math U See, but forgot things they already knew with Master Books. Master Books is not rigorous.
Saxon is rigorous and is a spiral program but is not from a Christian perspective.
We use Life of Fred which teaches Biblical truth and is more CM friendly. It is rigorous. But it does require a lot of reading since the lesson is in a story format. (My son thinks he should get to skip reading after doing his math. 🙂 )
So, you really have a lot of options. It just depends on what you want.