One might think that justification by faith alone is the easy way. In fact, just such a thing quite frequently has been thought. “What, you don’t even do anything? You wanna be a libertine or something?”
The objection has some force–but only when considered in general and in the abstract. It only has force, that is, when made a speculative morsel chewed by a mouth with no existential teeth.
“On the ground,” as it were, the situation is quite different. We humans like to be in control. We like to have something left to us to take care of. If there’s just something we can do–something to which we can point and say, “See? I did what I was told! I did good!”–we feel better, more assured. We like gold stars, pats on the back, a sense of achievement, of having done our bit.
For that reason, in particular and in the concrete there is nothing more difficult than believing that we are justified by faith alone. There is nothing more difficult than assenting to passive, rather than active, righteousness (that is, the righteousness of Christ rather than of ourselves) in relating to God.
Luther saw this, and it was one of his most important insights. Some deniers of justification by faith like to think of themselves as the mature ones, the purveyors of virtue, the upholders of Western Civilization, the builders of culture. In comes justification, out goes society, along with literature, the arts, and religion, to be replaced by licentiousness, barbarism, modernity (GASP).
In reality, there is nothing more childish than works-righteousness. The real theological-psychological-existential task is to submit to the righteousness of God, with all the fear and trembling that entails. Here’s Luther, from his opening section on the argumentum of Galatians at the opening of the 1535 Galatians commentary:
Ideo nos sic semper repetimus, urgemus et inculcamus hunc locum de fide seu Christiana iustitia, ut in assiduo usu servetur et accurate discernatur ab activa iustitia legis. (Ex illa enim et in illa sola doctrina fit et consistit ecclesia.) Alioqui non poterimus servare veram theologiam, sed fimus statim iuristae, ceremoniarii, legistae, Papistae, Christus obscuratur, et nemo potest in ecclesia recte doceri et erigi. Itaque si volumus esse praedicatores et doctores aliorum, oportet nos habere maximam curam harum rerum, et probe tenere hanc distinctionem iustitiae legis et Christi. Est quidem dictu facilis, sed experientia et usu est omnium difficilium, etiamsi diligentissime eam acuas et exerceas, quia in hora mortis vel aliis agonibus conscientiae propius concurrunt hae duae iustitiae, quam tu optes et velis.Martin Luther, Commentarius in Epistolam ad Galatas, Argumentum (WA 40.1, 49)
For that reason, we always repeat, urge, and stuff people full of this topic about faith or Christian righteousness so that it would be preserved and accurately distinguished from the active righteousness of the law. (For from and in that teaching alone does the church come into and remain in existence.) Otherwise, we will not be able to preserve true theology, but rather we immediately become jurists, ceremonialists, legal eagles, papists; Christ is obscured, and no one in the church can be taught and encouraged rightly. Therefore, if we wish to be preachers and teachers of others, it is right that we take the greatest care over these matters, and skillfully maintain this distinction between the righteousness of the law and the righteousness of Christ. True, it is easy to do so in words, but in experience and application it is the most difficult thing of all, even if you practice and train in it most carefully, because in the hour of death or other trials of conscience these two kinds of righteousness run together more closely than you desire or wish.The translation is my own.