1 Corinthians 3:2

"And I, brethren, could not speak unto you as unto spiritual." Why, in the first place, says he, though you had been perfect in spiritual things also, not even so ought you to be elated; for what you preach is not your own, nor such as yourselves have found from your own means. But now even these things ye know not as ye ought to know them, but ye are learners, and the last of all. Whether therefore the Gentile wisdom be the occasion of your high imaginations; that hath been proved to be nothing, nay, in regard to spiritual things to be even contrary unto us: or if it be on account of things spiritual, in these, too, ye come short and have your place among the hindmost. Wherefore he saith, "I could not speak unto you as unto spiritual." He said not, "I did not speak," lest the thing might seem to proceed from his grudging them somewhat; but in two ways he brings down their high spirit; first, because they knew not the things that are perfect; next, because their ignorance was owing to themselves: yea, in a third way besides these, by pointing out that "not even now are they able [to bear it]." For as to their want of ability at first, that perhaps arose from the nature of the case. In fact, however, he does not leave them even this excuse. For not through any inability on their part to receive high doctrines, doth he say they received them not, but because they were "carnal." However, in the beginning this was not so blame-worthy; but that after so long a time, they had not yet arrived at the more perfect knowledge, this was a symptom of most utter dulness. It may be observed, that he brings the same charge against the Hebrews, not however, with so much vehemence. For those, he saith, are such, partly because of tribulation: but these, because of some appetite for wickedness. Now the two things are not the same. […]

Not unfittingly, dearly beloved, do elders seem to bear a likeness to cows. Just as a cow has two udders to nurse her calf, so also elders ought to feed the Christian people with two udders: both the Old and the New Testaments.

And we have still to explain what is said by the apostle: "I have fed you with milk (as children in Christ), not with meat; for ye were not able, neither yet are ye now able." For it does not appear to me that the expression is to be taken in a Jewish sense; for I shall oppose to it also that Scripture, "I will bring you into that good land which flows with milk and honey." ... So that the whole matter may be conceived thus: As nurses nourish new-born children on milk, so do I also by the Word, the milk of Christ, instilling into you spiritual nutriment. ... And since the Word is the gushing fountain of life, and has been called a river of olive oil, Paul, using appropriate figurative language, and calling Him milk, adds: "I have given you to drink;" for we drink in the word, the nutriment of the truth. ... Wherefore the Holy Spirit in the apostle, using the voice of the Lord, says mystically, "I have given you milk to drink." For if we have been regenerated unto Christ, He who has regenerated us nourishes us with His own milk, the Word; for it is proper that what has procreated should forthwith supply nourishment to that which has been procreated. And as the regeneration was conformably spiritual, so also was the nutriment of man spiritual.

In the mysteries of Christ, he says, you are still infants, therefore I gave you milk to drink, that is, the simplest teaching, and did not offer you solid food, that is, more perfect teaching. Why? Because you were not yet able (to receive it). …

Thirdly, he gives the reason, lest they suppose that he withholds spiritual teaching from them through envy, which would be opposed to Wis (7:13): "Which I learned without guile and impart without envy." That is why he adds: for you were not ready for it. …

I have fed you with milk,....

Note, It is the duty of a faithful minister of Christ to consult the capacities of his hearers and teach them as they can bear. And yet it is natural for babes to grow up to men; and babes in Christ should endeavour to grow in Stature, and become men in Christ.

I have fed you with milk - I have instructed you in the elements of Christianity - in its simplest and easiest truths; because from the low state of your minds in religious knowledge, you were incapable of comprehending the higher truths of the Gospel: and in this state you will still continue. The apostle thus exposes to them the absurdity of their conduct in pretending to judge between preacher and preacher, while they had but a very partial acquaintance even with the first principles of Christianity.

I have fed you with milk - Paul here continues the metaphor, which is derived from the custom of feeding infants with the lightest food. Milk here evidently denotes the more simple and elementary doctrines of Christianity - the doctrines of the new birth, of repentance, faith, etc. The same figure occurs in Heb 5:11-14; and also in Classical writers. See Wetstein. And not with meat - “Meat” here denotes the more sublime and mysterious doctrines of religion. For hitherto - Formerly, when I came among you, and laid the foundations of the church. Not able to bear it - You were not sufficiently advanced in Christian knowledge to comprehend the higher mysteries of the gospel. Neither yet now ... - The reason why they were not then able he proceeds immediately to state.