Absolutely, Dave. Lilly published his book during the English Civil War, and the party that was in the ascendant was the Puritans, led by Cromwell, and very anti-divination, as well as anti-all-good-things-in-life (they closed the theatres, the taverns, the music centres, abolished Christmas, etc.) - his title was a prudent nod in the direction of the new masters of England.
In fact, there is nothing Christian about it (or any other religion). It's pure astrology, and Lilly used the texts and methods of the Continental and Arabic astrologers as his teaching texts, but synthesised them in a very user-friendly way. He was a born teacher.
A great classic, and Deborah Houlding does a good job of introducing it to modern audiences.