As newborn babes, desire the sincere milk of the word, that ye may grow thereby:
Newborn babes - altogether without "guile" (1 Peter 2:1; Revelation 14:5); in a specially tender relation to God (Isaiah 40:11). The childlike spirit is indispensable if we would enter heaven. "Milk" is here not elementary truths, as in 1 Corinthians 3:2; Hebrews 5:12-13; but in contrast to "guile," etc. (1 Peter 2:1); the simple Christian doctrine relished by the childlike spirit. The same "word of grace" which is the instrument in regeneration, is that also of building up. 'The mother of the child is also its natural nurse' (Steiger). The babe, instead of chemically analyzing, instinctively feeds on the milk; our part is not self-sufficient questionings, but simply receiving the truth in the love of it (Matthew 11:25).
Desire, х epipotheesate (G1971)] - 'have a yearning for,' or 'longing after,' natural to the regenerate; 'for as no one needs to teach newborn babes what food to take, knowing instinctively that a table is provided for them in their mother's breast,' so the believer of himself thirsts after the word of God, (Psalms 119:1-176.)
Of the word, х logikon (G3050)] - not as Alford, 'spiritual;' nor "reasonable," as Romans 12:1: logos in Scripture means, not the reason, but the WORD; the context requires so here: logikos (G3050) follows the meaning of logos (G3056), 'word.' James 1:21, "Lay apart all filthiness, etc., and receive with meekness the engrafted WORD," confirms the English version here.
Sincere - `guileless.' Irenaeus says, 'Heretics mix chalk with the milk.' "The" implies that, besides the well known pure milk, there is no other unadulterated doctrine: the Gospel alone can make us guileless (1 Peter 2:1).
Grow. 'Aleph (') A B C, Vulgate, read, 'grow unto salvation.' Being BORN again, we are also to grow unto (perfected) salvation, the end of our growth. 'Growth is the measure of that, not only rescue from destruction, but positive blessedness, implied in salvation' (Alford).
Thereby - Greek, 'IN it:' fed on it: in its strength (Acts 11:14). 'The word is to be desired with appetite as the cause of life, swallowed in the hearing, chewed as cud is, by rumination with the understanding, and digested by faith' (Tertullian).