Mark 9:23 — “If Thou Canst Believe” or “If Thou Canst”? Who Is Being Challenged?

“If thou canst believe, all things are possible to him that believeth.” — Mark 9:23

The desperate father says to Jesus, “If thou canst do any thing, have compassion on us.” The received reply turns the condition toward him: “If thou canst believe.” The critical text reads to ei dynē—roughly, “As for your ‘if you can’” or “The ‘if you can’!”

In either form Jesus refuses the suggestion that his power is the uncertain element. The question is faith, and the father immediately cries, “I believe; help thou mine unbelief.”

A pointed answer in two forms

The critical wording is terse and difficult. Jesus echoes the man’s phrase with astonishment before declaring possibility to the believer. Scribes could add “believe” from the next clause to complete the grammar and make the challenge explicit.

The received text has its own rhetorical strength. The repeated verb produces a balanced exchange: “If thou canst do”—“If thou canst believe.” It is not a claim that faith contains independent power. The second half places possibility within believing reliance on the one who can act.

The words are close enough for loss or supplementation during transmission. A scribe may omit pisteusai after seeing the same root in pisteuonti later in the sentence; another may supply it because the initial phrase seemed suspended. Internal arguments therefore depend heavily on how one punctuates a spoken retort that no manuscript recorded with quotation marks.

The received reading also matches the father’s answer exactly. He does not defend the propriety of his earlier “if.” He confesses belief and asks for help with unbelief—the two realities named by Christ’s direct challenge.

“All things are possible” must remain attached to God’s will and promise. Biblical faith is not an instrument for making every desire inevitable. Here it rests on Christ’s mercy and authority over an evil spirit that the disciples could not cast out.

The father’s answer also functions as an internal translation of the debate. Whatever punctuation is chosen in verse 23, he understands Jesus to demand believing reliance and to expose unbelief. That response limits speculative renderings of the compressed critical phrase. A textual form should explain the next speech, and the received challenge does so without requiring English quotation marks around an echo of “if.”

The fuller reply should stand. It gives the exchange a transparent personal address without changing its theological center. The critical form may preserve an abrupt idiom, but the received balance is not a dull correction; it is a memorable answer that explains the confession Mark records in the next breath.

Sources and further reading

• F. H. A. Scrivener, ed., The New Testament in the Original Greek according to the Text Followed in the Authorised Version (Cambridge, 1894).
• Michael W. Holmes, ed., The Greek New Testament: SBL Edition (Society of Biblical Literature and Logos Bible Software, 2010), text and apparatus.
• Bruce M. Metzger, A Textual Commentary on the Greek New Testament, 2nd ed., notes on the stated passage.
• Mark 9:14–29; Matthew 17:14–21; Luke 9:37–43.