Congregation leaving worship service as gunman fired. Note: Estimates of the current population of the Coptic Church range from 10 million to 60 million members worldwide. Theologically, Coptic Christianity is very similar to Roman Catholicism and Eastern Orthodoxy. They profess to be genuine followers of Jesus Christ and a part of His worldwide Church. But, as with Catholicism, they tend to emphasize meritorious works in salvation along with liturgical ritual rather than salvation through a personal relationship with Jesus Christ.