The words used in Hebrew are not the same as those used for God. The word used by +Paul for the believers is agios (holy), which is the same word used for God. There is a definite distinction.
This is another example of biblical linguistics. Another drastic example is 1 Cor 13:3. All western Bibles say:
This appears in the Greek Majority Text and subsequently ends up in Textus Receptus, and from there on in just about every western Bible.
Older Greek texts use a word that differs only by one letter, and means "to boast" rather than to "be burned."
Thus, instead of kauchesomai the word is kauthesomai; someone misread one single letter as θ instead of χ, and changed the meaning of the whole verse and all the Bibles in the west.
So the text should read, "and if I surrender my body to be boast"???? No wonder Peter said some of Paul's writings were difficult to understand.
My search turned up a few words for "believers", and I see nothing wrong with that. There are several ways to express the same idea in English also. For example, in 1 Cor. 6:5, Paul uses the word "adelphos" (brethren) for believer. In 1 Cor. 14:22, he uses "pisteuo". In Gal. 6:10 he uses the related "pistis" in referring to believers as the "household of faith". I didn't see any confusion about Paul's references to believers vs. to God.