Martin Luther's seeking after God led him to some conclusions about God.
Luther objected to a saying attributed to Johann Tetzel, a papal commissioner for indulgences: "As soon as the coin in the coffer rings, the soul from purgatory springs"; and he insisted that since pardons were God's alone to grant, those who claimed indulgences absolved buyers from all punishments and granted them salvation were in error. Christians, he said, must not slacken in following Christ on account of such false assurances. (Wikipedia)
Henri Nouin as well.
In Return of the Prodigal Son, for example, Nouwen describes love and forgiveness as unconditional. Though this is not a novel idea, Nouwen's approach is arguably unique as we approached this theme from the angles of the younger son, the elder son, and the father. Each captures the unconditional quality of love and forgiveness in their own way. The younger son's life shows how the beloved lives a life of misery by thinking he can be loved only by meeting certain qualifications of the lover (which he fails to meet). The elder son's actions shows how the beloved can be depressed because he thinks he should receive greater love because he has done all the right things (i.e., that he has met these qualifications). The father alone understands how to love and forgive and is able to do so and be happy. Nouwen explains that we are the younger son at times (when we think we don't deserve the love or the forgiveness) and the elder son at times (when we think we deserve love or that another doesn't deserve it more than us), but that we are all called to be like the father (and that only by being like the father can we come closer to being loved as we should be loved). (Wikipedia)
"I am deeply convinced that the Christian leader of the future is called to be completely irrelevant and to stand in this world with nothing to offer but his or her own vulnerable self." -In the Name of Jesus, 1989