Exactly 503 years ago today, Martin Luther nailed the Ninety-Five Theses to the church door in Wittenburg, Germany, launching the Protestant Reformation. The act was far less a public press release as it was an invitation to an academic debate, much like publishing a controversial article in an academic journal. But thanks to the recent invention of the Gutenberg press, the document was translated, reprinted, and distributed widely across Germany and beyond. Before, only a brave few had dared to question the establish religion. Now, those questions were becoming the talk of the street.

Remembering the birth of the Reformation on October 31 isn’t simply an act of historical nostalgia, like we might remember the Battle of Gettysburg or the landing of the Mayflower. The doctrine that the Reformation re-established (for it was there all along in scripture) remains core to the identity of who we are as Christians today.

Take justification by faith alone, the lynchpin of Luther’s own conversion and message. The more I engage in street evangelism, the more I see almost every conversation—whether it be with a Catholic, a Mormon, or an agnostic—comes down to this issue. We as humans simply cannot convince ourselves that we are basically sinful. And so, whenever I ask someone why they think God would let them into heaven, they instinctively run off a list of their good deeds. ‘Sure, I do bad things,’ most admit, ‘but I’m a good person, and I think God’s fine with that.’

Even as Christians, justification by faith alone can be one of the most difficult realities to wrap our brains around. I lived for years under the pressure of trying to be a good enough Christian to make God happy with me. Every night, I’d lie in bed thinking of all the ways I’d failed and resolving to try harder tomorrow. It wasn’t until I started to grasp the message of Romans, first through listening to John Piper exposit the book and then sitting under the preaching of my pastor, Ken Murphy, that the weight and beauty of justification by faith alone hit me.

And it changed my life. I experienced the incredible freedom that comes from realizing I, in my sinfulness, cannot do anything to merit the favor of a holy God. Romans 4 says it best: “Now to him who does not work, but believes in him who justifies the ungodly, his faith is accounted for righteousness.” When Christ, through His sacrifice, took my sin and gave me His righteousness, suddenly God could look upon me as righteous—and nothing can change that. I can rest. I can fall in love with Christ instead of constantly working to please Him. I can truly love others.

The Reformation didn’t stop at justification—it also laid out principles that establish the core of the Christian life. The five “solas,” Sola Scriptura, Sola Fide, Sola Gratia, Solo Cristo, and Soli Deo Gloria, stand in direct opposition to man’s attempt to work his way to God. Every established religion requires the Bible (or other holy book) plus tradition. Faith plus good deeds. Grace plus merit. Christ plus other prophets, saints, or holy men. And ultimately, a little bit of God’s glory plus a lot of man’s self-righteousness.

The five ‘solas’ of the Reformation strip us of all of that. Instead, we are left with the most beautiful, most simple, and most powerful gospel. Simply Christ, through simple, God-given faith, through His grace, by His Word—to His glory alone.

Now that’s a message worth spreading.