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.
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.
The NIV Study Bible tells us in a footnote for Acts 20:28: "his own blood. Lit[erally] 'the blood of his own one,' a term of endearment (such as 'his own dear one,' referring to his own son)." - Zondervan, 1985.
Famous trinitarian scholar J. H. Moulton says about this:
And for the above reason noted trinitarian NT scholar and translator William Barclay rendered Acts 20:28:
"... the Church of God which he has rescued through the blood of his own One."
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:
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.
"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.