Let me note, with Tom Van Dyke, I'm not even certain that Franklin's statements in this "Defense" represent his true beliefs, or whether he's merely acting as an advocate. I do believe Franklin found some expressions of the Christian faith more preferable to others. And that Arminianism and unitarianism were preferable to the hard core Calvinism that sought to railroad Samuel Hemphill.
This part is interesting (I have added paragraph breaks for clarity; what is italicized is in the original; the boldface is mine):
Hemphill is condemn’d for advancing this Piece of Heresy, viz. They who have no other Knowledge of God and their Duty, but what the Light of Nature teaches them; no Law for the Government of their Actions, but the Law of Reason and Conscience; will be accepted, if they live up to the Light which they have, and govern their Actions accordingly.
To this our stern Authors answer, Will the Heathen be accepted of God, by living up to the Light which they have, and governing their Actions accordingly? then, say they, there is no need of Christ’s Merits and Satisfaction, in order to our Acceptance with God.
... The Holy Scriptures represent his Mission as a general Benefit, a Benefit which Regards all Men, and in Fact, tell us that Christ dyed for all.
And can any imagine that our good God, as is here suppos’d, will eternally damn the Heathen World for not obeying a Law they never heard of; that is, damn them for not doing an Impossibility. Surely none can imagine such a thing; except such as form their Ideas of the great Governor of the Universe, by reflecting upon their own cruel, unjust and barbarous Tempers, as our Authors seem to do.
If God requir’d Obedience to an unknown Law, Obedience to the Gospel from those that never heard of it, or who never were in a Capacity or Circumstances of being reasonably convinc’d of it, it would be in the first Place manifest Injustice; for surely, Promulgation or Publishing of a Law must be allow’d necessary, before Disobedience to it can be accounted criminal.
It is utterly impossible to reconcile the contrary Notion with the Idea of a good and just God; and is a most dreadful and shocking Reflection upon the Almighty. In the next Place, we should find the Mission of our Saviour so far from being a general Benefit, as the Scripture teaches, that on the contrary it would be but a particular one, distributed only to the smallest Part of Mankind: But, which is more, this Mission of our Saviour wou’d be a very great Misfortune and Unhappiness to the greatest Part (three Fourths) of Mankind.
For it is probable, that without this Necessity of Obedience to an unknown Law, many would be able to save themselves by a good Use of their Reason and the Light of Nature; whereas by the Mission of our Redeemer, and the Imposition of an unknown Law, a Law which they could not observe (I mean what is peculiar to Christianity) they are reduc’d to an utter Impossibility of being sav’d.
I do not think that these Observations can be contradicted without saying Things very injurious to the Deity, and therefore erroneous. Agreable to the general Notion here advanc’d are the Sentiments of St. Paul in Rom. 4:15 where he says, For where no Law is there is no Transgression. And Rom. 5:13 Sin is not imputed when there is no Law. See also Rom. 2:14, 15.
I know that some Passages of Scripture are adduc’d by the Maintainers of this Notion to prove the Truth of it. ... And give me leave to remark here by the by, that if after all requisite Care and Pains, Reason clearly teaches the Truth of such or such a Proposition, and that we find in the holy Scriptures some Passage that seems to contradict the clear Decisions of Reason, we ought not, for we really cannot, admit that Sense of the Passage that does so, altho’ it shou’d be receiv’d by all the Divines, that call themselves orthodox, upon Earth; So that any Man must be altogether in the right to look out for another Sense of the Passage in Question, which will not contradict the clear Decisions of Reason.This Principle is to be extenden only to Propositions, which evidently contradict the clear and manifestly well-founded Decisions of Reason in general (as in the Case before us;) and I say that such Propositions, such Doctrines cannot be contain’d in divine Revelation; so that we must look for another Sense of the Passages, by which they wou’d pretend to establish these Propositions or Doctrines; we must, I say, look for a Sense agreeable to Reason and the known Perfections of God; and it is absolutely impossible to reconcile the Opinion here contradicted to either; and if this Notion be not to represent the Almighty, as stern, arbitrary, inexorable, & pray what is?
As for those Passages of Scripture, which are often adduc’d to prove the absolute Necessity of all Men’s believing in Jesus Christ without Distinction, in order to Salvation; Reason, common Sense, Equity and Goodness oblige us to understand and apply them only to those to whom infinite Wisdom has thought proper to send the Gospel.
This passage contains a number of notable theologically liberal, heterodox for the time sentiments.These Gentlemen can hardly take it amiss to be advis’d to take the utmost Care of saying any thing, or interpreting Scripture after a Manner injurious to the infinite Justice, Goodness and Mercy of God, and contradictory to Reason. If the christian Scheme of Religion be not a reasonable one, they wou’d make but a dull Piece of Work on’t in attempting to vindicate the Truth of it.
1. It's undeniable that works are at least part of the Franklin's justification scheme as he admits that some folks, even without Jesus coming would be able to save themselves "by a good Use of their Reason and the Light of Nature." Note, he's not saying just the Jews living according to the law of the Old Testament, though they might qualify under such. He's more generally applying the principle to all men (Ancient Greeks, Romans, the other noble pagans) who by their reason live lives of virtue according to the light of nature.
2. So why did Christ come? To save more people. To streamline the process of getting into Heaven. According to a theory prevalent among fellow Christian-Deists at the time, Jesus perfectly typified the law of nature, determinable from reason. Though, Jesus' example is clearer than what a typical man's reason could determine for himself. If men are saved in some way by their virtue (and such saving virtues can be determined from reason and the senses alone) and Jesus perfectly modeled such, knowing Jesus' clearer example would lead to greater levels of salvation, accordingly.
3. Franklin doesn't seem comfortable with the notion that a large percentage of humanity are destined for or will go to damnation. I do see in Franklin's overall work, an endorsement of the notion of a future state of rewards and punishments. And in one letter, purgatory where imperfect souls are prepared for Heaven. It's doubtful he believed in an eternal Hell for anyone.
Benjamin Rush once noted how his newly found Arminian principles of the universality of Christ's Atonement led to a belief in the eventual salvation of all mankind. Franklin repeats the Arminian tenet that "Christ dyed for all."
The overall tenor of the passages seem to indicate more than Jesus just dying for all, but that a great deal of humanity (perhaps all?) would benefit, some kind of hopeful universalism.
4. Franklin also concedes there are different ways to interpret the Bible and that he endorsed injecting a sense of "Reason, common Sense, Equity and Goodness ... infinite Wisdom ... infinite Justice, Goodness and Mercy of God" into his interpretation of the texts. And he would reject implications that made God look "as stern, arbitrary, inexorable." Further he called out the understanding of the Bible of "the Divines, that call themselves orthodox,..."
In other words, Franklin rejected the understanding of Christianity that holds "this is what the Bible teaches, and if you don't like it, tough luck, take it up with God."