I've been thinking about my mission so much lately. The people, the areas, the memories, all of it. I miss it more than I can even describe.
While on my mission, I had so many people ask me why baptism was so important. Or, if they had already been baptized, they would ask why it was important to be baptized again. We would always explain that it's because baptism needs to be done by the proper authority (the priesthood) and that we need to receive The Gift of the Holy Ghost. More often than not, people would tell us that they already received direction through the Holy Ghost and that they didn't see how being baptized would change that.
First of all, I think it's important to understand the difference between the Light of Christ and the Gift of the Holy Ghost. The Light of Christ is something in all of us. Everyone is born with the Light of Christ regardless of their culture, location, or religious beliefs. It's what helps us to discern good from evil and to have a desire to do what is right. The Holy Ghost speaks to us through the light of Christ. I love Elder Wirthlin's explanation of the difference in this video:
I also love this quote from President Boyd K. Packer, "the Holy Ghost can work through the Light of Christ. A teacher of gospel truths is not planting something foreign or even new into an adult or a child. Rather, the missionary or teacher is making contact with the Spirit of Christ already there. The gospel will have a familiar ‘ring’ to them"
Basically, the light of Christ is a part of us, then the Holy Ghost speaks to us through the Light of Christ. After we are baptized, we work and endure to the end which helps the Light of Christ to grow in us. As we nurture that light that is within us, the Holy Ghost will be able to further guide us in our lives.