"In essentials, unity; in non-essentials, liberty, and in all things, charity."
The origin of this phrase is not important to this argument, but for the curious, here's the Wikipedia link that will start off the newbies with non-authoritative information.
This maxim seems to be saying that, if the area of discussion is a "non-essential", then it is not rational to view a Christian as sinful or non-Christian merely because they disagree with you on said non-essential.
What criteria should we use to figure out which bible teachings are "essential" and which aren't?
Let's review what modern conservatives have to say:
Credo House gives the following criteria:
1. Historicity: Does the doctrine have universal historical representation?2. Explicitly Historical: Does the history of the church confess their centrality?3. Biblical Clarity (Perspicuity): Is the doctrine represented clearly in Scripture?4. Explicitly Biblical: Does any passage of Scripture explicitly teach that a certain doctrine is essential?...Again, these four criteria, I propose, must all be present. I think I am committed to this. If one or more is lacking concerning a particular doctrine, I believe that it is not possible for one to legitimately argue for its core necessity. As well, all four feed off each other and are somewhat self-regulating. In other words, if someone doubts whether something is clear in Scripture, all he or she has to do is look to history. If something is not clear in the Scripture, we will not find that it passes the test of historicity. This is why it is of vital importance that Christians not only be good exegetes, but also good historians.
The minimum age and/or other traits a girl must reach/acquire before she can be legitimately married in God's eyes, has no "universal" historical representation. That subject is not made "universal" by either the bible or the church fathers. Singular expressions of opinions do not make something "universal". Tertullian was a Montanist, but that hardly makes his opinion a universally recognized teaching. The same with Origen's spiritualizing the text to get rid of contradictions/errors, and Irenaeus' belief that Jesus lived to be around 50 and had an earthly ministry of more than 10 years.
The minimum age and/or other traits a girl must reach/acquire before she can be legitimately married in God's eyes, has no history of the church confessing it's centrality. Nowhere in church history do we ever find statements about minimum age for marriage being declared to be "central".
The minimum age and/or other traits a girl must reach/acquire before she can be legitimately married in God's eyes, has no clear basis in the bible. When we think of doctrines that have "clear basis in the bible", we think of monotheism, existence of God, Jesus being the son of God, his rising from the dead, etc, etc. Apparently then, "clear basis in the bible" requires multiple attestation. God's opinion on the minimum age of marriage is hardly witnessed in the bible to that degree.
Norman Geisler's criteria for identifying essential teaching is to stress the creeds, and give the reader an overview of the Roman Catholic, the Reformed, and the Anabaptist criteria for essential doctrine. But this doesn't help, since none of those sources even talks about the minimum age of marriage.
From this brief survey, it would appear that the minimum age a girl must be in order to be eligible for marriage in God's sight, cannot be "essential" teaching, it can only at best be "non-essential" (i.e., your salvation or orthodoxy cannot be compromised by the age you believe a girl becomes ready to marry), in which case, by your own creed, you must allow "liberty". That is, you cannot disfellowship or excommunicate the man in your African congregation who is a member of a Bushman tribe and who has married a 9 year old girl consistent with the tribe's beliefs.
As an atheist, I'd cease being friends with anybody if I found out they were a pedophile, since I detest the practice in all forms. There is no "how do we know what essential teaching is" to muddy up my moral intuitions.
You can escape this rebuttal by refusing to believe in the maxim stated at the beginning of this article, but you'd probably take a very big hit socially and personally, since you'd then become a bigot, and you'd give up on Christian friends as soon as they disagreed with you on anything in the bible.
Face it, friend, you are sure that your god hates marital pedophilia as much as he hates bestiality, yet your god apparently chose to plainly prohibit the latter and say absolutely nothing about the former.