“As a surgeon does not hesitate to cut off a gangrenous hand to save a life, so evil and destructive practices, though precious to us as a very part of our lives, must be sacrificed to save the soul [person].”614

These enigmatic words,75 we may reasonably assume from their context, relate to the cost of taking up the cross to follow Jesus.

God will subject everyone to fiery trials. He does this to believers and unbelievers alike during their earthly lives (James 1:1–18). He will also do this to believers’ works when they stand before the judgment seat of Christ (cf. Matt. 25:14–46; 1 Cor. 3:10–15). He will do this to unbelievers when they stand before Him at the great white throne judgment (Rev. 20:11–15). This seems to me to be the best interpretation. It takes “everyone” literally and is consistent with other revelation.

To be ‘salted with fire’ seems then to evoke the imagery of temple sacrifice, but the victims who are ‘salted’ are now the worshippers themselves. Their dedication to the service of their suffering Messiah is like that of a burnt offering, total and irrevocable.

In this context it speaks of one who follows Jesus as totally dedicated to God’s service, and warns that such dedication will inevitably be costly in terms of personal suffering.77

Among the various uses for salt in the ancient world the most prominent are as a preservative or cleansing agent or as flavouring.78 In either case it symbolises the beneficial (καλόν) influence of the disciple on society, most obviously in Mt. 5:13 with the declaration ὑμεῖς ἐστε τὸ ἅλας τῆς γῆς.79 Salt was a necessity of life: ‘The world cannot endure without salt’ (Sop. 15:8; cf. Ben Sira 39:26).

Jesus continued to use salt as a figure for testing. He said that tests from God, like salt on food, are good for us. Salt preserves food, prevents decay, and enhances flavor. The trials that God allows people to experience should have similar beneficial effects on them (cf. James 1:2–4). However, if salt becomes bland, it will not achieve its intended results (cf. Matt. 5:13).

Here the allusion is to salt used in domestic life. “Salt is good” in that it is a necessity for life and a preservative. Christians are likewise a source of spiritual life for the world. They restrain evil and thus preserve the moral order. Christians, however, can and sometimes do cease to function as the “salt” of the world, and it is against this that Jesus warned.

So disciples who have lost the ‘salting’ (v. 49) that makes them καλόν are no longer effective. The threat of being ‘thrown out’ which follows this saying in Matthew and Luke is absent in Mark, but the thought may nevertheless be inferred from the threat of γέεννα and unquenchable fire in vv. 43–48