I personally do not think that using fear to motivate people makes any sense in a religious context. I do not think that true virtue can exist if you are acting out of fear of Hell. So to me, the better motivation would be love. I would be the idea that God loves you and you, hopefully, love God and so shouldn't you try to be the way that God wants you to.
But this is a way more modern vision of God and would not work with Edwards' theology. In Edwards' theology, people don't have the kind of personal relationship with God that we imagine today. It was more of a theology of God as a harsh father.
So a different approach might seem better to me, but I don't think it would be consistent with Edwards' theology.
Fear is the ultimate motivator. If you look at history, or even current events, fear gets us to act. Take a look at how travel has changed within the United States because of terrorism. We fear what could happen on a plane and therefore, millions of travelers daily go through a routine that adds an extra 5-60 minutes to their travel plans. These aren't minutes spent for fun, they are spent in response to fear.
I agree that it is not right to motivate religiously out of fear, however, according to Christian theology hell is very real. If you read the bible, God's wrath and grace come across clearly. I've heard speakers articulate that God is both 100% grace and 100% justice.
Edwards speech by the end gives that offer of grace. His sermon reads almost like a story with an inciting incident (man's sin), rising action (all those metaphors of how we are hanging on essentially by a thread) and a climax (wherein late in the speech he offers a chance to make a decision to accept Christ) and falling action and resolution (the glorious idea of heaven which is obtained through grace).
I think using God's grace as a motivator would be very effective, but this would only work for people who could accept their sinful nature. We don't like to be told we are messed up in any way. Thus, he used fear to get to share grace. Today, ministers are much more apt to focus on that grace and I think pointing out the depths to which God would go to seek and save "the lost" would likely be a motivator better than fear, but it would have to be used on the right audience.
That being said, many religions, especially the older, more traditional Christian ones, use fear and guilt as powerful motivators. In Puritan days, the idea that humans were born sinful, and that only through pious living and adherence to religious ideals might they convince an "angry" God to allow them into heaven was central to their belief system.
Appealing to fear is appealing to a basic human emotion, so it can be effective, but I don't think it's ethical to knowingly and willfully use fear as a motivator. Fear is an extrinsic motivator - you are afraid something bad will happen to you so you modify your actions as suggested. Pride, love, conscience, these are all intrinsic motivators. We react to these because we feel better doing it, because we want to. Fear is a temporary motivator most times, the intrinsic motivators are often much more permanent.
I think it was spot on and it is an outrage that so few people talk like this today. For me, it was only the fear of hell of wrath of god that brought me to salvation, and it was only in light of this that i truly saw the full range and awsomeness of gods amazing grace.
For if we were not bound for hell, why would we care about what god did? THERE IS SURELY NO OTHER reason than this that christ was sent to die for us, and it is necessary therefore, that hell and gods punishment should be at the front of our minds. For it is from this that we were saved into his eternal grace.
This important fact cannot be downplayed, downsized, or made to seem unimportant or possibly rude.
However, some people, due to their personal personalities and spirits, like to focus more on other things. Other things can possibly motivate people better than this, yet it is paramount that while those things DO motivate people better, that we do not lose sight for a second the truth of this sermon.