After the class, I was asked a question about the meaning of baptism by fire. It seemed to this person that there was the Father, the Son, the Holy Ghost, and Fire. While they knew that wasn't correct, they didn't understand what baptism of fire is.
I've been pondering that question a lot. I plan on working it into my next lesson. I've done some preliminary research and found some interesting things. For me, baptism by fire means the sanctifying process of the Holy Ghost.
Two things happen when we repent. We become justified and we become sanctified. Justification is the payment of the debts incurred when we sinned. If we don't repent and change our hearts to God, we will have to pay for our sins ourselves (D&C 19). Sanctification, on the other hand is the process of changing our hearts during the repentance process. It is what makes us more like God. I believe the Holy Ghost both justifies and sanctifies us. Paying for our sins alone does not make us holy.
That is what the baptism of fire is. I didn't understand why the concept of baptism by fire wouldn't be clear.
Then I looked up "Baptism by Fire" in Wikipedia. Wikipedia indicated that baptism by fire is known as the punishment of fire that comes to those who reject Christ. The article further stated that it was different then baptism by the spirit. Baptism by the spirit was what happened to Christ's followers on the Day of Pentecost. I was shocked! That's not my understanding. In fact, the Wikipedia article went on to talk about how Mormon's view Baptism of Fire and how it differs from the rest of the Protestant world. It certainly does if that is their viewpoint! (By the way, I don't completely agree with all that was said, but that is irrelevant to my point right now.)
I found a Conference talk by Elder Bednar, Clean Hands and a Pure Heart. http://lds.org/general-conference/2007/10/clean-hands-and-a-pure-heart?lang=eng
We are commanded and instructed to so live that our fallen nature is changed through the sanctifying power of the Holy Ghost. President Marion G. Romney taught that the baptism of fire by the Holy Ghost "converts [us] from carnality to spirituality. It cleanses, heals, and purifies the soul. ... Faith in the Lord Jesus Christ, repentance, and water baptism are all preliminary and prerequisite to it but [the baptism of fire] is the consummation. To receive [this baptism of fire] is to have one's garments washed in the atoning blood of Jesus Christ"
Hence, as we are born again and strive to always have His Spirit to be with us, the Holy Ghost sanctifies and refines our souls as if by fire (see 2 Nephi 31:13-14, 17). Ultimately, we are to stand spotless before God.