In support of the idea that the doctrines contained in the Book of Mormon must have been from a divine source because they were not taught in Joseph Smith’s contemporary Christianity, Tad Callister argued:
… contrary to contemporary beliefs, the Book of Mormon refers to a premortal existence in Alma 13 (see Alma 13:1–11)
However, the manner in which Alma 13 refers to a premortal existence is roughly consistent with how it was invoked in sermons from the time.
As pointed out and discussed by churchistrue, Alma 13:3 points more towards the foreknowledge of God and less to an actual pre-existent state, and it does so similar to others from the time. For example, here’s Alma 13:3 (emphasis added):
And this is the manner after which they were ordained—being called and prepared from the foundation of the world according to the foreknowledge of God, on account of their exceeding faith and good works; in the first place being left to choose good or evil; therefore they having chosen good, and exercising exceedingly great faith, are called with a holy calling, yea, with that holy calling which was prepared with, and according to, a preparatory redemption for such.
And here is Jacob Wood from a sermon delivered in Massachusetts in 1828 (emphasis added):
The celebrated John Wesley a distinguished opposer of Calvinism and advocate of Arminian principles has given us a plain statement of this subject in his Sermon on Predestination. He says The scripture tells us plainly what predestination is it is God’s fore appointing obedient believers to salvation not without but according to his fore knowledge of all their works from the foundation of the world. And so likewise he predestinates or fore appoints all disobedient unbelievers to damnation not without but according to his fore knowledge of all their works from the foundation of the world. We may consider this a little farther. God from the foundation of the world fore knew all men’s believing or not believing And according to this his fore knowledge he chose or elected all obedient believers as such to salvation and refused or reprobated all disobedient unbelievers as such to damnation. Thus the scriptures teach us to consider election and reprobation according to the fore knowledge of God from the foundation of the world.
Dozens, perhaps hundreds, have taught the idea
Terryl Givens recently wrote a book on the topic of the premortal existence in various thought across time (When Souls Had Wings). He recently commented:
The LDS faith is the only significant Christian denomination teaching this doctrine today. But it turns out, literally dozens—perhaps hundreds—of poets, mystics, philosophers, theologians and pastors have taught this same principle across the centuries. (emphasis added)
In the same article, Givens seems to indicate that Joseph Smith may have been exposed to these ideas:
We too often think that Joseph (Smith) started with a clean slate, repudiating the entire Christian past and starting out fresh, only teaching that which came to him direct from the Heavens; but he emphatically resisted any such expression,” Givens said. “His was a generous mind, unafraid to embrace truth wherever he found it and bring it home to Zion.
Elsewhere, though, he notes that the brand of pre-mortal existence Joseph Smith taught was idosyncratic and he is aware of no evidence of influence:
One should not assume that because I am LDS, I must be writing with the intention of mustering arguments on behalf of an LDS theology. If that were indeed the case, I would have failed entirely. For in the entire history of the idea of a premortal soul, virtually no version matches Joseph Smith’s conception or shows evidence of having influenced his own.
It should be noted that the allusion to pre-mortal existence in Alma 13 is more consistent with some broadly accessible Christian views on the topic; the differentiation Givens refers to came mostly in Joseph’s later teachings on the topic as the concept of a pre-mortal existence was further resolved.