A verse commonly cited by those who oppose salvation by faith alone is John 6:29, where it is argued that faith itself is a “work.”
Jesus says:
“This is the work of God, that ye believe on him whom he hath sent.”
At a surface level, and when stripped of its context, the statement may appear to support that conclusion. But careful exegesis requires that we read the verse in light of its immediate context.
Consider verse 28 of the same chapter:
“Then said they unto him, What shall we do, that we might work the works of God?”
Notice first how the question assumes that a plurality of works is necessary. “What shall we do, that we might work the works of God?” The question itself presupposes that multiple deeds are required to merit God’s favor.
In verse 29, Christ deliberately echoes their vocabulary, employing the word “work” in an ironic and corrective sense. He mirrors their terminology not to affirm their theology, but to expose its flawed premise. In effect, Jesus undermines their works-based assumption by redefining the issue entirely. The only “work” He identifies is not a meritorious act at all, but the non-meritorious reception of God’s gracious provision.
The apostle Paul makes this distinction explicit in Romans 4:5:
“But to him that worketh not, but believeth on him that justifieth the ungodly, his faith is counted for righteousness.”
If faith were itself a “work,” this verse would collapse into absurdity. It would read:
“But to him that worketh not, but worketh, his work is counted for righteousness.”
Paul’s contrast only makes sense if believing and working are categorically distinct. Faith, by definition, is not a work.
The same truth is affirmed in Ephesians 2:8–9:
“For by grace are ye saved through faith; and that not of yourselves: it is the gift of God:
Not of works, lest any man should boast.”
Commentator Charlie Bing rightly observes:
Jesus answers simply, “This is the work of God.” Jesus does not concede to their request for a list of works, but in a play on their request for “works,” He uses only the singular word “work” as something that must be done.
In other words, He answers, “If you want to know what you have to do to become acceptable to God, simply believe in the One whom He sent.” Jesus gives nothing else to “do” but believe; that is all that God commands and all that God requires (cf. 1 John 3:23).
In a world full of religions that all have a different list of things to do to know God, get to heaven, or find salvation, how refreshing it is that Jesus teaches we must only and simply believe that He was sent by God to be our Savior from sin. If biblical Christianity loses this clear teaching, we become like all the other religions of the world that teach we must work to earn our eternal salvation.
— Grace, Salvation, and Discipleship: How to Understand Some Difficult Bible Passages, p. 123
Far from contradicting sola fide, Jesus’ statement in John 6:29 confirms it. He not only rejects the assumption that a plurality of works is necessary to merit God’s favor, but explicitly declares that the singular “work” God requires is to believe. That, quite simply, is faith alone.