As it concerns The Spirit of the Disciplines by Southern Baptist minister Dallas Willard:

The spiritual disciplines that are supposedly necessary for spiritual formation are not defined in the Bible. If they were, there would be a clear description of them and concrete list. But since spiritual disciplines vary, and have been invented by spiritual pioneers in church history, no one can be sure which ones are valid. Willard says, [W]e need not try to come up with a complete list of disciplines. Nor should we assume that our particular list will be right for others.” The practices are gleaned from various sources and the individual has to decide which ones work the best. Willard lists the following: voluntary exile, night vigil of rejecting sleep, journaling, OT Sabbath keeping, physical labor, solitude, fasting, study, and prayer. Willard then lists “disciplines of abstinence” (solitude, silence, fasting, frugality, chastity, secrecy, sacrifice) and “disciplines of engagement” (study, worship, celebration, service, prayer, fellowship, confession, submission).

Willard offers a discussion of each of these, citing people like Thomas Merton, Thomas a Kempis, Henri Nouwen, and other mystics. We are told that practices like solitude and silence are going to change us, even though the Bible does not prescribe them. Willard writes, “This factual priority of solitude is, I believe, a sound element in monastic asceticism. Locked into interaction with the human beings that make up our fallen world, it is all but impossible to grow in grace as one should.” So if we cannot grow in grace without solitude, how come the Bible never commands us to practice solitude? The same goes for many other items on Willard’s list.

Willard tells us that the list of disciplines he provides is not exhaustive. Others can be pragmatically determined. He says, “As we have indicated, there are many other activities that could, for the right person and upon the right occasion, be counted as spiritual disciplines in the strict sense stated of our previous chapter. The walk with Christ certainly is one that leaves room for and even calls for individual creativity and an experimental attitude in such matters.” However, there is a serious problem with Willard’s logic here. Earlier he rejected such practices as self-flagellation, exposing the body to severities including being eaten by beetles, being suspended by iron shackles, and other means of severely treating the body in order to become more holy. Willard rejects these on the following grounds: “Here it is matter of taking pains about taking pains. It is in fact a variety of self-obsession—narcissism—a thing farthest removed from the worship and service of God.”

Willard had admitted that there is no clear list of the disciplines and that each person might choose different practices through pragmatic means. This does not give sufficient ground for rejecting such practices as self-flagellation. So Willard resorts to arguing that those who do such things have bad motives. But he cannot really know their motives, perhaps they determined that these practices “worked” using the same means Willard offered. If pragmatic tests are the means of determining which practices are valid, and if these people feel closer to God and more like Christ through their practices, then Willard has no valid way of rejecting their practices. Having no valid argument, he resorts to an invalid ad hominem argument.

He cannot have it both ways. Either God’s Word determines both how we come to God and how we grow in grace, or humans determine these things by pragmatic means. Willard has chosen the later. But then he steps in and tells us that some practices are wrong, even though they fit his own criteria for validity. If a person feels that sleeping in a tiny stone crevice with all the heat being sucked out of his body makes him more spiritually disciplined, then who is to say that is wrong? Had he been willing to submit to the authority of Scripture, Willard could have refuted these practices based on Colossians 2:21-23.

Pastor Bob DeWaay, The Dangers of Spiritual Formation and Spiritual Disciplines: A Critique of Dallas Willard and The Spirit of the Disciplines

See also:

DELUSIONS OF DALLAS WILLARD

THE CULT OF GURU RICHARD FOSTER

“CELEBRATION OF DISCIPLINE” BY RICHARD FOSTER AN ENCYCLOPEDIA OF THEOLOGICAL ERROR

SPIRITUAL FORMATION: JUST SAY NO

SPIRITUAL FORMATION IS PIETISM REIMAGINED