At the headwaters of the Reformed tradition

 ... we have this summary statement from Karl Barth's colleague on the Divinity faculty at the University of Basel: 

Luther becomes a reformer because he cannot reach the assurance of salvation in the system of the Roman Catholic church; Oecolampadius becomes a reformer because, in the Roman Catholic church, he does not find the new creature in Christ sufficiently realized. For Luther it is about justification; Oecolampadius says in connection with 1Thessalonians 4:3, “God’s will is our sanctification.” With Luther, faith stands in the foreground, with Oecolampadius, that which flows from faith, the “piety,” the “sanctity,” the “charity,” both individually and in the totality of the “mystical body of Christ.” Luther represents a Christianity more strongly characterized by Paul, Oecolampadius by John. 

—Ernst Staehelin, Breakthrough to the Reformation, pp. 128-129.

In case you were ever wondering what it means to belong to the Reformed tradition, this, I would suggest, is what it originally meant.