When it comes to having epistemological certainty that one's beliefs are true, Mormonism has the so-called "burning in the bosom" experience. Please see this related question to find a few references.
However, a more general experience, supposedly accessible to all Christians, is the the so-called "inner witness of the Holy Spirit". For example, the Westminster Confession, in chapter 1.5, states the following:
We may be moved and induced by the testimony of the Church to an high and reverent esteem of the Holy Scripture, and the heavenliness of the matter, the efficacy of the doctrine, the majesty of the style, the consent of all the parts, the scope of the whole, (which is to give all glory to God), the full discovery it makes of the only way of man's salvation, the many other incomparable excellencies, and the entire perfection thereof, are arguments whereby it doth abundantly evidence itself to be the Word of God; yet, notwithstanding, our full persuasion and assurance of the infallible truth, and divine authority thereof, is from the inward work of the Holy Spirit, bearing witness by and with the word in our hearts.
William Lane Craig, a renowned Christian apologist, puts it this way (emphasis mine):
[...] These bothers and sisters endured horrible oppression and atheistic indoctrination by the Marxist regime and yet did not abandon Christ. As I emphasized in my answer to Question #13, evidence varies from generation to generation and from place to place and is accessible only to those privileged few who have the education, leisure time, and resources to explore it. God has provided a more secure basis for our faith than the shifting sands of evidence and argument, namely, the indwelling Holy Spirit.
Moreover, this conclusion seems in line with New Testament teaching on the witness of the Holy Spirit. While non-believers reject New Testament teaching, Christians should take it seriously. Ponder, then, John's words:
And the Spirit is the witness, because the Spirit is the truth. . . . If we receive the testimony of men, the testimony of God is greater; for this is the testimony of God that he has borne witness to his Son. He who believes in the Son of God has the testimony in himself. He who does not believe God has made him a liar, because he has not believed in the testimony that God has borne to his Son (1 John 5:6-10).
As Christian believers we have the testimony of God living within us, the Holy Spirit, whose testimony exceeds in force all human testimony.
So in answer to your question, Kyle, I think that in fact God will not allow someone to be in a position in which the rational thing for him to do is to reject God and Christ and separate himself from God. Given that God is essentially all-loving, I'm inclined to say that such a thing will not only never happen, but that it is, indeed, impossible. It follows that Christians who have apostatized have done so in defiance of the Holy Spirit's work by quenching or grieving the Spirit, so that what they did was in the end irrational.
Does that imply, Adam, as your sceptic says, that I think "evidence is unimportant when compared with faith?" No, because he's drawing a false contrast, comparing apples with oranges. Faith is not the issue here, but the ground for faith. Must the ground for faith be evidence? That is the question. We've already seen that evidentialism is bankrupt. Many of the things we know are not based on evidence. So why must belief in God be so based? Belief in God and the great truths of the Gospel is not a blind exercise of faith, a groundless leap in the dark. Rather, as Plantinga emphasizes, Christian belief is part of the deliverances of reason, grounded in the inner witness of the Holy Spirit, which is an objective reality mediated to me from God.
What is true is that evidence, as it is defined in these discussions, plays a secondary role compared to the role God Himself plays in warranting Christian belief. Should we, then, ignore strong evidence if it shows that our faith is probably false? Of course not! My work as a philosopher exemplifies the effort to confront objections to Christian belief squarely and to answer them. But most Christians in the world don't have that luxury. For them they may have to hold to their Christian belief even though they lack an answer to the alleged defeater. What I insist on is that, given the witness of the Holy Spirit within them, they are entirely rational in so doing.
Question: what is the difference between the "burning in the bosom" of Mormonism and the more general "inner witness of the Holy Spirit" of Christianity? Are they essentially the same thing?
Q & A
Q. The question is probably intended to be about beliefs of one specific denomination, The Church of Jesus Christ of Latter-day Saints. If so, it's more correct to name that church. (Unless the question is about general beliefs of a group of churches in the more general movement, in which case such a question gets a lot more difficult to answer on behalf of many churches.)
A. This is a 'comparative-christianity' question (see the tags). Therefore, I would like to see a comparison of terminology, where 'burning in the bosom' is a term coined by Mormonism and the "(inner) witness of the Holy Spirit" is a more general concept employed by the rest of Christendom more generally. If there are nuances inside each group, pointing them out would be a plus.
Q. While there is occasional misunderstanding here, it's also worth noting that members of The Church of Jesus Christ of Latter-day Saints are Christians by any reasonable definition-- their own, a simple analysis of beliefs, and as generally accepted. (many references available at the Wikipedia link)
A. Some would beg to differ:
- Are there any Christian denominations that consider LDS (Mormons) to be Christians?
- What is the basis that many mainstream Christian groups justify labeling groups like the Mormons and Jehovah Witnesses as Non-Christians?
Q. Why is the "inner witness" characterized as "more general"? Are there references available which identify that terminology as accepted throughout "Christianity"? The overlong citation from one source seems inadequate to make that kind of case.
A. The primary reason is the ample biblical support for the concept. See for example https://bible.knowing-jesus.com/topics/The-Witness-Of-The-Holy-Spirit. Since virtually all Christians accept the Bible as inspired, it follows that they very likely have come across these verses (at least the fraction of Christians who habitually read the Scriptures) and, therefore, you would expect them to be familiar with the concept.
If interested in more evidence, with a quick cursory search you can find many books on the topic, such as:
- The Witness of the Spirit: An Essay on the Contemporary Relevance of the Internal Witness of the Holy Spirit
- Wonderful Holy Spirit: Experience the Reality of God's Presence and Power in Your Life
- The Holy Spirit and Christian Experience
- Experiencing the Holy Spirit
- Good Morning, Holy Spirit: Learn to Recognize the Voice of the Spirit
- Holy Spirit I Hunger For You