"In the name of the father son and holy spirit"

Translation: Kwa jina la baba mwana na roho mtakatifu

[Gzeebzee]

Would it be better to add an extra "na" between father and son?

[DeArchitect]

In a normal way of speaking, both sentences don't sound natural at all:

In the name of the Father, and of the Son and of the Holy Spirit (Ghost) : Kwa jina la Baba, na la Mwana, na la Roho Mtakatifu

That's what you'll hear from most of the priests. So, by considering that it's just for learning purposes, you have to answer as how Duo asks.

[Klgregonis]

If this is a standard phrase, it should be in the data base as that standard phrase. Not as an alternate, requiring an alternate translation.