In 155 a.d. the Christian philosopher and apologist Justin Martyr wrote an account about how the church worshiped in that day. I have included a link to the referenced article in Christianity Today here. In reading it you will see interesting references to the Trinity, communion (for believers only), the brining of offerings, the ministry of the Deacon, the teaching and reading of the Word, and several other interesting things.
In one reading it appeared Justin Martyr was asserting that baptism was performed for the remission of sins, which is not consistent with good Biblical doctrine. The other thing that Justin asserted (which is taught in the Catholic church) is that the Eucharist (bread) becomes the actual body and blood of Christ once consumed by the believer.
Anyhow, this is an interesting glimpse into one account of how some early Christians worshiped.