From the first introduction of Smeagol in The Fellowship of the Ring, there is an overarching sense that he had a purpose in this entire narrative. Frodo originally expresses regret that Bilbo did not kill him when he had the chance, but Gandalf reminds them that there very well might be some type of purpose that no one can understand.
At the end of all things, and the fires of Mount Doom, Frodo made the decision that he did not want to give up the ring after all. It had possessed him to such a great degree that he could not bear the thought of throwing it away.
That is often times the way it is.
We need a push to make that change complete. For further, that turned out to be Smeagol biting off his finger with the ring on it before carelessly tumbling over into the fire himself.
Frodo however recognized the importance of what Smeagol did for him.
Any temptation we have is somewhat similar. Recently, members of Teen Challenge Vermont visited my church. As long as the men who shared their testimonies still felt like they were in control, they were unwilling to confront the addiction they had struggled with. However, a sense of hitting rock-bottom came through in all of their testimonies. They finally found a point where they could not do anything else, so they sought out this wonderful program for help in overcoming these struggles in their life.
Frodo was in a very similar situation. Until he literally hit rock bottom and had that ring taken away from him, he was not able to give it up. He was addicted to it even though he knew he had to get rid of it and had to fulfill the mission. It had intoxicated him to the point that only the outside force of Smeagol was able to force that change. Kind of like hitting rock-bottom, I imagine having your finger bit off by an evil creature is not a pleasant experience, but deliverance was found through that trial.
We might want to make all the changes in the world, and we might know that it would be good for us to perhaps start or stop doing certain things. However, we have a hard time with that final push. We have a hard time actually starting or stopping. We need the outside force to help us. Even though it might not always be pleasant, the push can help put us on the right track in a way that we were unwilling or unable to do on our own.
 J.R.R. Tolkien, The Lord of the Rings (New York: Houghton Mifflin Harcourt, 2002), 945, Kindle Edition.
Smeagol is a pathetic creature who is finally revealed in the second half of The Two Towers. Driven by a desire to possess the ring again, he had trailed the fellowship for a majority of their journey together, and now that Frodo and Sam find themselves alone, he makes his move. His move is rather unsuccessful however, and he is captured by the hobbits and forced to serve them. However, upon seeing the kindness of the hobbits, Smeagol began to respond to that and seem to change.
I think that we often identify with this on some level especially one we know people who profess to have become Christians. Perhaps this might be after a concert or conference, but there is this effect where people want to change their lives when they have these types of emotional experiences. The problem of course comes a month later when the emotional high wears off. It is hard to tell if these people have really changed and if it was a deep, worldview change that is indicative of a true commitment to Christianity.
Of course, I'm not in the business of judging people's salvation. That is ultimately not my job. However, there are people who is a go right back to how they began and it doesn't seem as if that professed Christianity made any difference. The problem is of course that the New Testament is rather clear. Having a relationship with Jesus Christ will change you little by little.
Smeagol led the hobbits through the Dead Marshes, and during that journey, they saw a Nazgul flying on one of their fell beasts. This encounter with adversity pushed away this change to some degree.
That sometimes all it takes. People have the best of intentions and professing to be Christians, but when they come to the point in their lives where the going gets tough again, they fall away. This is similar to one of Jesus' parables about the seeds that were scattered and the different ways in which they grew.
Smeagol is a lesson in caution for all of us. We are able to change, but if we do not cling to that change and hold to our newfound faith in Jesus Christ, it is really easy to go backwards. It is really easy to profess Christianity but really not allow Jesus Christ into our lives. We will not see the change that can take place if we do not do that.
 J.R.R. Tolkien, The Lord of the Rings (New York: Houghton Mifflin Harcourt, 2002), 623, Kindle Edition.