First, your story has to put a face on the theme or issue you are writing about. Having a strong character that represents or stands for something that your reader can relate to is a powerful weapon in your arsenal. Wield that weapon with purpose. When your reader relates to the character in such a way, then that character and their aim also represents them, in a way. If you can touch a reader in such a way, you might have a fan for life.
Second, a great story has to tap into emotions. Your story has to trigger some kind of deep emotional response from your readers. You may be looking to incite empathy, sadness, or envy with some scenes. Events that evoke emotional responses weigh heavy on readers and stick with them. A touching heartfelt story is a hard one to forget. For example, if you’ve ever read Tuesday’s With Morrie by Mitch Albom, I’d bet a vital organ that you still remember that powerful story. It is so easy to relate to and nearly impossible to forget.
A great story will also connect us to the message you’re trying to get across and make it vitally important. In other words, it hooks us on the level of importance and humanizes us in that way. You may write a story about political or corporate corruption, but you use conflict and action to tug at the better angels in us all. In the end, we may not focus on that corruption but instead we see the need for honesty and integrity, and revisit the values that make us good people. It gives us a peek into our own souls about who we are and what we value. That is powerful indeed.