'Great Celtic Christians' is the fourth volume in The Celtic Prayer Book series by Ray Simpson. It is an alternative resource for churches who would like a prayer book that offers something different to their regular services. It is also a relevant and useful book to those who want to take part in individual daily prayer or group prayer.

The book contains many inspiring features, such as a commemorative dates calendar, prayers, poems, and scripture readings. It also includes recommendations for creative activities, which will prove particulalry useful to church and group-prayer.