William Burkitt on John 3:5

Nicodemus not rightly understanding Christ's meaning in the former verse, our Saviour is pleased to explain himself in this, and tells him, That the birth he spake of was not natural, but spiritual, wrought in the soul by the Spirit of God, whose working is like water, cleansing and purifying the soul from all sinful defilement.

Learn hence, That the regenerating change is wrought in the soul by the Spirit of God, which purifies it from its natural defilement, and renews it after the divine likeness and image. We never understand divine truths aright, till Christ opens our understandings; till then they will be denied, nay, perhaps derided, even by those that are profoundly learned.