Dr. Gregg Frazer likewise shares a similar personal understanding of "Christianity" (which he likewise understands as "God's understanding," etc.). Yet for the thesis of his book, he uses a late 18th Century American consensus understanding. It is a 10 point test that forms a lowest common denominator among the Presbyterians, Congregationalists, Lutherans, Baptists, Anglicans and Roman Catholics. In short, the sects affiliated with the vast majority of the population of late 18th Cen. America. It is not quite "the Nicene Creed" simpliciter. But it (as I see it) in some meaningful way resembles the orthodox minimum, "mere Christianity" approach -- an understanding that stretches from St. Athanasius to C.S. Lewis.
There are some differences. For instance, the capital O Orthodox Church (of the Eastern bent) do not (as far as I understand) accept the doctrine of original sin, which is part of Dr. Frazer's 10 point test. Yet, they are included in the Nicene minimum. They aren't included in Dr. Frazer's minimum because (surprise) they had virtually no (or no) presence in late 18th Century America.
Dr. Frazer's personal test for "Christianity" is arguably stricter than his late 18th Century American test. One has to believe not just Jesus as 2nd Person in the Trinity, but be "born again" and accept "Christ only." With this, it's still hard to grasp fully how conservative evangelicals view who is or is not a "real Christian" as they themselves disagree. They split, for instance, on whether Roman Catholics are "real Christians." (When Pope John Paul II and Mother Teresa were still alive, I once observed Pat Robertson, nicely enough, say both of them were going to Heaven.)
As far as Anglicans are concerned, a good deal of them in the late 18th Century could qualify as "real Christians" according to evangelical standards. Some not. Some, like Thomas Jefferson, were deistic or unitarian and didn't accept orthodoxy. Others, though orthodox, didn't consider themselves "born again" but worshipped the Trinity through the Anglican liturgy (39 Articles and the Book of Common Prayer).
I don't think, for instance, George Washington was an orthodox Trinitarian Christian. But were he, it was, as my friend Mary V. Thompson of Mt. Vernon argues, through quietly worshipping Anglican liturgy. In short, even if he were orthodox, George Washington still was not a "born again, evangelical Christian."
I write this because Bill Fortenberry takes issue with Gregg Frazer's test for late 18th Century American Christianity. Rather, Fortenberry thinks what he understands as God's definition taught from the pages of the Bible alone should prevail. Yet, even though he believes the Bible teaches the Virgin Birth, Trinity, an orthodox understanding of the atonement, he doesn't accept belief in these as non-negotiables for determining who is a "Christian." (He explains his position in more detail here in this comment forum.)
Gregg Frazer responded to me in an email which he gave me permission to publish. Though he did note, time may forbid him from getting "sucked in" to an extended discussion in the comments:
WSForten has clearly not read – or paid attention to – pages 17 and 18 of my book and phrases such as “For the purposes of this study” and “all of the individuals identified as theistic rationalists in this study were affiliated with one or more of these denominations, as were forty-seven of the fifty-five members of the Constitutional Convention” and “the definition is designed to identify who was not a Christian or who would not be considered Christian by any of the denominations” and “These definitions are designed more to identify who was not a deist or Christian than to identify who was.”
WSForten’s beef is with the 18th-century American Christians, not me. He does suffer from the problem ably demonstrated by OFT – taking individual verses out of context. For example, what does it mean to believe that Jesus is the Christ? That carries a lot of meaning and “baggage” (good baggage) with it and any contemporary reader of John’s epistle would know that in a way that an average contemporary American reader (or 17th-century English reader) would not. For example:
WSForten’s notion that for His atoning sacrifice to be satisfactory, Jesus need not be God, but “only” sinless ignores several critical points – especially #7:
1) The sacrifice must be righteous, not merely innocent (Rom. 5:18-19) – righteousness is the result of obedience (Rom. 6:16); mere innocence (not having yet fallen) is not sufficient
2) An infinite/eternal sacrifice was required to affect all men & all time; only an eternal being could make such a sacrifice (Heb. 9:13-14) – i.e. for those both before & after His incarnation
3) Jesus is the heir to glory, so only He could make us fellow heirs/sons (Gal. 3:16, 29; 4:5-7)
4) His unique intercessory position – as the Son, His proper place is at the right hand of the Father (Rom. 8:33-34; Heb. 8:1 [Christ “has taken His seat”]; Heb. 7:25)
5) God’s expression of His great love for us in sacrificing His own Son (John 3:16; I John 4:10)
6) The sacrifice must be voluntary; there is no justice in condemning the innocent without his volition (Rom. 5:6-7; John 10:17-18)
7) The One Who makes a will must die to release the inheritance/promises (Heb. 9:16-17) – Christ’s death satisfied both covenants because He is God and made both covenants (Jer. 31:31-33; Heb. 8:8).
No single verse contains all that is necessary to be believed in order to be saved. Individual verses make individual points/claims to particular individuals or in particular contexts. Rom. 10:9-10, for example, doesn't mention belief in the Messiah -- it mentions belief in the resurrection and in the lordship of Jesus. Paul says in I Cor. 15:16-17 that faith is worthless without the resurrection. Earlier in I Cor. 15, he lays out the gospel as he preached it and "by which you are saved" (what one must believe) including the atonement ("Christ died for our sins"), the resurrection, and the need for grace. There he does not mention belief in the Messiah.
Re the idea that any sinless man could be the sacrifice: later I Cor. 15:45-49 explains that the second Adam/sacrifice/Messiah had to be "a life-giving spirit," "from heaven," and "heavenly" by nature -- no mere man who hadn't yet sinned could fulfill that requirement. There is also the matter of original sin and the fact that no mere man COULD be without sin.
Re WSForten's notion that some things are actions, not beliefs: one can not or will not do some actions unless one believes something. OFT mentions "repentance" -- a persistent theme in the teaching of Jesus and John the Baptist. One cannot take the action of repenting in the biblical sense without believing that one is a sinner and in need of a savior -- these are other necessary beliefs beyond simple belief that Jesus is the Messiah.
Re the virgin birth: even Locke's standard requires belief in the virgin birth and the deity of the Christ (although he doesn't recognize it). Locke's rule is that you must believe God's Word/promises. This is where knowing the whole concept/meaning behind "Messiah" is important. Part of God's promise concerning the Messiah was that He would be born of a virgin (Isa. 7:14) and that He would be God (Isa. 9:6). You cannot believe in the biblical Messiah -- God's promised One -- without believing in these elements. You can't make up your own concept of a Messiah and then say that you believe in God's concept of a Messiah.
Re John 20:30-31: as OFT pointed out, John is specifically speaking about the signs that Jesus did and that he reported. In addition, John does NOT say that you ONLY have to believe that Jesus is the Christ. He simply says that he wrote the record he did so that a reader would believe that Jesus is the Messiah AND that He is the Son of God -- i.e. God. In the verses immediately preceding 30-31 (John 20:24-29), for example, Thomas does not believe in the RESURRECTION/that Jesus defeated death -- that is what he comes to believe. He doesn't mention that Jesus is the Messiah -- but he does affirm that Jesus is God! That is the object of his belief.
One final point: Satan and his demons believe that Jesus is the Messiah -- are they saved/Christians? They know the facts of Who Jesus is (Matt. 8:29; Luke 8:28; James 2:19). Jesus being the Messiah is simply a matter of fact. What requires faith -- saving faith -- is all that goes with that fact.
Clarification: re #7 in the reasons that Jesus (specifically) and only Jesus had to be the sacrifice, the Greek word translated "covenant" is the word for "will" (as in last will & testament).