I edited the question to incorporate the information the OP had posted in three separate answers (which I believe was a misperception on his part that the Answer space was for discussion). The combination of this information, which even were I wrong about his intent in posting the answers, clearly demonstrates that OP wants a Biblical discussion about the Trinity. That is, he puts forth a counter-example where regular names are used with in the names of and concludes that the singular in the name of means that Father, Son, and Holy Spirit is one person.
In this case, I don't think the question can be properly answered without an appeal to the original Hebrew/Aramaic/Greek or whatever it was written in and a further discussion of the implications of how that was then translated into English. Sounds like a question for biblical scholars.
If you would like to edit the question to make it about countable/uncountable nouns and see if you can preserve the original intent of the post while substituting a non-doctrinal context, you are welcome to do so. Removing the references to the Trinity might help make it clear which parts of it are about English, and are therefore on-topic, which in turn translates into a greater likelihood of re-opening by the community.