Adiaphora is the plural of the word adiaphoron, which, in philosophy, refers to a thing that exists outside of moral law. An adiaphoron is an action that is neither condemned nor approved by morality. Adiaphora means “indifferent things,” that is, things that are neither right nor wrong, spiritually neutral things.
The concept of adiaphora originated in Stoicism. The Stoics maintained that, if one’s reason was flawed, one’s emotions would become destructive and overwhelming. They taught that happiness comes from living in line with what is logical, rational, or “natural.” In Stoicism, there are three classes of human behavior. The pursuit of things like virtue and justice is good, displaying their opposites is bad, and the rest is adiaphora—moral neutral ground or things to which nature is indifferent.
Adiaphora, in biblical terms, would be the “disputable matters” mentioned in Romans 14:1 (the ESV calls them “opinions”). We are not to quarrel over them. Some things are right, because the Bible says they are right; other things are wrong, because the Bible says they are wrong. But some things the Bible neither condemns nor approves. We often refer to these issues as “gray areas” or matters of conscience. We could also call them adiaphora. For example, the Bible clearly promotes truth-telling and condemns lying. But what about writing fiction? As long as everyone knows it’s fiction, that’s adiaphora.
We can also think of the “non-essentials” of the faith as adiaphora. Teachings on the timing of the rapture, the number of angels, or the identity of the two witnesses in Revelation 11 are non-essential to the faith; they are adiaphora. On the other hand, doctrines such as the deity of Christ, salvation by grace through faith, and the bodily resurrection are essential and non-negotiable.
In one sense, there is no such thing as adiaphora in human behavior. Paul says, “Whatever you do, whether in word or deed, do it all in the name of the Lord Jesus, giving thanks to God the Father through him” (Colossians 3:17). Everything we do—even things that seem morally neutral—fall under the banner of goodness if we do them for God’s glory. And even things good in themselves can be done with impure motives and thus be dishonoring to God (Isaiah 1:10–15). Succeeding in our work, going for a run, playing games with friends, and all the other things we do that don’t seem either good or bad, can fall squarely under the banner of goodness when we do them in a way that glorifies Christ with thanksgiving.