The Apostle humbles the pride of human understanding by reminding us that all knowledge in this life remains partial. Even the saints, though illuminated by grace, do not yet behold divine things perfectly. Therefore prophecy, teaching, and spiritual understanding are all incomplete, suited to the weakness of the present condition. Men often become proud of knowledge because they forget how little they truly comprehend. But the soul that grows in charity becomes increasingly aware of the vastness of God and of its own dependence upon Him. (St. John Chrysostom)

“We know in part.” Augustine frequently returns to this truth in order to teach humility. In this life we walk more by faith than by sight. We grasp many things dimly, as through shadows and signs. Even when the mind understands something true about God, it cannot yet comprehend Him fully. Thus the Christian must remain both teachable and humble, avoiding the presumption of thinking that divine mysteries can be exhausted by human reasoning. For God surpasses all that the human mind can contain. (St. Augustine)

“But when that which is perfect is come.” The Apostle directs the soul toward the life to come, where partial knowledge shall give way to fullness. The Fathers explain that this perfection refers not to earthly achievement, but to the completion of the soul in the vision of God. In heaven the faithful shall no longer know God indirectly through signs, sacraments, or figures, but shall behold Him more clearly according to the measure granted them. Thus the present life is a state of pilgrimage and preparation, while the future life is fulfillment. (St. John Chrysostom)

“That which is in part shall be done away.” This does not mean that truth itself disappears, but that imperfect modes of knowing pass away when fullness arrives. A child no longer needs the lessons proper to infancy once maturity is reached. So too the helps suited to our present weakness will cease when the soul enters eternal communion with God. Yet charity remains throughout both states, because love is already the beginning of that perfection for which the soul was created. The more charity grows, the more the soul is prepared for the vision that shall one day complete it. (St. Augustine)

Sources: St. John Chrysostom, Homilies on First Corinthians, Homily 34; St. Augustine, sermons and writings on divine knowledge, humility, and the vision of God.