Trinitarians, for obvious reasons, prefer this translation of Acts 20:28 - "... to shepherd ["feed" in some translations] the church of God which He purchased with His own blood." - NASB. This certainly seems to be excellent evidence for a "Jesus is God" doctrine.
But there are 2 major uncertainties about the proper translation of Acts 20:28. Either one of those uncertainties completely nullifies any trinitarian "evidence" proposed for this Scripture!
First, even some trinitarian Bibles translate this verse, "the church of the Lord." - NEB; REB; ASV; Moffatt. Since Jesus was often referred to as "the Lord," this rendering negates any "Jesus is God" understanding for Acts 20:28.
Yes, even the popular trinitarian The New International Dictionary of New Testament Theology, p. 838, Vol. 2, Zondervan Publ., 1986, uses this translation for Acts 20:28 also: "to feed the church of the Lord"!
And the respected, scholarly trinitarian work, A Textual Commentary on the Greek New Testament, p. 480, United Bible Societies, 1971, explains about this first uncertainty concerning the translation of Acts 20:28. Although, for obvious reasons, preferring the rendering "the church of God" at this verse, this trinitarian work admits that there is "considerable degree of doubt" about this "preferred" rendering. They admit that "The external evidence is singularly balanced between `church of God' and `church of the Lord.'"
Second, even some trinitarian Bibles render this verse, "to care for the church of God which he obtained with the blood of his own Son." - RSV, 1971 ed.; NRSV; NJB; (also see TEV and GNB).
The New Testament Greek words tou idiou follow "with the blood" in this scripture. This could be translated as "with the blood of his own." A singular noun may be understood to follow "his own." This would be referring to God's "closest relation," his only-begotten Son.
Famous trinitarian scholar J. H. Moulton says about this:
"something should be said about the use of [ho idios, which includes tou idiou] without a noun expressed. This occurs in Jn 1:11, 13:1; Ac 4:23, 24:23. In the papyri we find the singular used thus as a term of endearment to near relations .... In Expos. vi. iii. 277 I ventured to cite this as a possible encouragement to those (including B. Weiss) who would translate Acts 20:28 `the blood of one who was his own.'" - A Grammar of New Testament Greek, Vol. 1 (Prolegomena), 1930 ed., p. 90.
Highly respected trinitarian New Testament scholars Westcott and Hort present an alternate reason for a similar rendering:
"it is by no means impossible that YIOY [huiou, or `of the Son'] dropped out [was inadvertently left out during copying] after TOYIDIOY [tou idiou, or `of his own'] at some very early transcription affecting all existing documents. Its insertion [restoration] leaves the whole passage free from difficulty of any kind." - The New Testament in the Original Greek, Vol. 2, pp. 99, 100 of the Appendix.
And A Textual Commentary on the Greek New Testament, p. 481, tells us:
"Instead of the usual meaning of dia tou haimatos tou idiou [`through the blood of the own'], it is possible that the writer of Acts intended his readers to understand the expression to mean `with the blood of his Own.' (It is not necessary to suppose, with Hort, that huiou may have dropped out after tou idiou, though palaeographically such an omission would have been easy.) This absolute use of ho idios is found in Greek papyri as a term of endearment referring to near relatives. It is possible, therefore, that `his Own' (ho idios) was a title which early Christians gave to Jesus, comparable to `the Beloved'."
Therefore, we can see that a rendering similar to RSV's "the church of God which he obtained with the blood of his own son [or `beloved']" is obviously an honest, proper rendering.
Although the UBS Committee didn't actually commit itself one way or another on this rendering of tou idiou at Acts 20:28, it did mention that "some have thought [it] to be a slight probability that tou idiou is used here as the equivalent of tou idiou huiou [`his own Son']." - p. 481. Obviously this includes those trinitarian scholars who translated the Revised Standard Version (1971 ed.) and Today's English Version.
Note the the even more certain conclusion of trinitarian scholar, Murray J. Harris, after an extensive analysis of this passage:
"I have argued that the original text of Acts 20:28 read [THN EKKLHSIAN TOU THEOU HN PERIEPOIHSATO DIA TOU AIUATOS TOU IDIOU] and that the most appropriate translation of these words is 'the church of God which he bought with the blood of his own one' or 'the church of God which he bought with the blood of his own Son' (NJB), with [HO IDIOS] construed as a christological title. According to this view, [HO THEOS] refers to God the Father, not Jesus Christ.
"If however, one follows many English versions in construing [IDIOS] adjectivally ('through his own blood'), [HO THEOS] could refer to Jesus and the verse could therefore allude to 'the blood of God,' although on this construction of [IDIOS] it is more probable that [THEOS] is God the Father and the unexpressed subject of [PERIEPOIHSATO] is Jesus. So it remains unlikely, although not impossible, that Acts 20:28 [HO THEOS] denotes Jesus." - p. 141, Jesus as Theos, The New Testament Use of Theos in Reference to Jesus, Baker Book House, Grand rapids, Michigan, 1992.
Since so many respected trinitarian scholars admit the possibility (and even the probability) of such honest alternate non-trinitarian translations for Acts 20:28, this Scripture can't honestly be used as proof for a trinity concept.
Acts 20:28 ("God...with his own blood") (Defending the NWT)
ACTS 20:28 (IN Defense of the NWT)
Does Acts 20:28 really say that God bought the church with his "own" blood? (SFBT)
Acts 20:28 ("God...with his own blood") (Examining the Trinity)
A Response to Alleged New World Translation "Errors" (Jehovah's Witnesses United)
"The Sahidic Coptic version...does not speak of 'the church of God which he purchased with his own blood,' (Acts 20:28) (NWT and Coptic)
(Also see the SCRIPTURE INDEX.)