A.T. Robertson Commentary Mark 9:24

"Straightway the father of the child cried out, and said, I believe; help thou mine unbelief." — Mark 9:24 (ASV)

Cried out (κραξας). Loud outcry and at once (ευθυς). The later manuscripts have "with tears" (μετα δακρυων), not in the older documents.

I believe; help my unbelief (Πιστευω: βοηθε τη απιστια). An exact description of his mental and spiritual state. He still had faith, but craved more. Note present imperative here (continuous help) βοηθε, while aorist imperative (instant help) βοηθησον, verse 22. The word comes from βοη, a cry and θεω, to run, to run at a cry for help, a vivid picture of this father's plight.