“Vain” (εἰκῇ) denotes an action performed arbitrarily, without valid justification, purpose, or reason—essentially, done in vain. The term conveys the idea of acting without cause or meaningful intent. In contrast, “vain” (κενός) is an adjective meaning “empty,” “without content,” “without effect,” or “without result.” Because these two words are translated with the same English word, the lack of clarity will produce confusion in understanding.
εἰκῇ expressed the lack of a purpose, not object. In 1 Corinthians 15:2, Paul clearly declares the good news he preached among the Corinthians through which they were saved, unless their faith had no purpose, that is, they did not direct their faith at Christ concerning His death on behalf of sins and resurrection three days later.
Κενός, on the other hand, conveys a sense of emptiness—such as being empty-handed. In one of Christ’s parables, He speaks of a vineyard owner who sends his servant to collect some of the fruit. In response, the men hired to tend the vineyard beat the servant and send him back to his master empty-handed (Mark 12:3). The term is also used to describe plans that are without purpose, such as when the nations rage against the Messiah and plot in vain (Acts 4:25).
In the Millennial Kingdom, a Jew who is angry with his brother without cause (εἰκῇ) will be in danger of judgment (Matthew 5:22). God has not given human government the authority of the sword in vain; they are to avenge and execute wrath upon all who practice evil (Romans 13:4). A fleshly mind, vainly puffed up, delights in false humility and the worship of angels, introducing things not seen, and thereby cheats others out of their freedom in Christ—bringing in religious superstition rather than truth (Colossians 2:18). Such individuals do not hold fast to the Head, from whom the whole body is nourished; instead, they submit to the principles of the world system and construct a self-made religion based on the commandments and teachings of men (Colossians 2:20–22).
When it comes to emptiness (κενός), it pertains both to works and words. If Christ is not risen from the dead, then the proclamation of the witnesses is empty—without content or power (1 Corinthians 15:14). We are not to be deceived by empty words, nor by philosophy and empty deceit (Ephesians 5:6; Colossians 2:8). Words that lack substance bring about the wrath of God. These include sayings, quotes, and other phrases labeled as “Christian” or “godly,” yet are void of truth. From such emptiness proceed fornication, covetousness, idolatry, coarse jesting, and foolish talking. These are the fruit of the sons of disobedience—those who are unpersuaded by the truth (Ephesians 5:3–5). Philosophy and empty deceit are rooted in the traditions of men and the elementary principles of the world system; they are not according to Christ (Colossians 2:8).
In regard to the gospel for salvation, there are those who do not direct faith toward Christ, for their belief has no purpose. Their claim of belief is based on the traditions of their fathers, not on personal trust in the facts of the gospel message: “I came from a Christian family,” or “I was born into a Christian nation.” Faith is taking God at His word; it is not a work of man. Yet some will hear the message of Christ’s death on behalf of sin and His resurrection three days later, according to the Scriptures, and base their salvation not on these facts of what Christ has done, but on their own ability to keep on believing. This is not faith; it is presumption, for the purpose of gaining favor and blessings from others. If a person has changed their mind (repented), the mind is permanently changed. However, if a person merely parrots a message but does not truly believe it, there has been no repentance, and they will recant their belief when either persecution comes or when they do not receive what they hoped to gain by claiming they believe.