1 Corinthians 10:2

"That our fathers," saith he, "were all under the cloud, and all passed through the sea; and were all baptized unto Moses in the cloud and in the sea; and did all eat the same spiritual meat; and did all drink the same spiritual drink; for they drank of a spiritual Rock that followed them: and the Rock was Christ. Howbeit with most of them God was not well pleased." And wherefore saith he these things? To point out that as they were nothing profited by the enjoyment of so great a gift, so neither these by obtaining Baptism and partaking of spiritual Mysteries, except they go on and show forth a life worthy of this grace. Wherefore also he introduces the types both of Baptism and of the Mysteries. But what is, "They were baptized into Moses?" Like as we, on our belief in Christ and His resurrection, are baptized, as being destined in our own persons to partake in the same mysteries; for, "we are baptized," saith he, "for the dead," i.e., for our own bodies; even so they putting confidence in Moses, i.e., having seen him cross first, ventured also themselves into the waters. But because he wishes to bring the Type near the Truth; he speaks it not thus, but uses the terms of the Truth even concerning the Type. Further: this was a symbol of the Font, and that which follows, of the Holy Table. For as thou eatest the Lord's Body, so they the manna: and as thou drinkest the Blood, so they water from a rock. For though they were things of sense which were produced, yet were they spiritually exhibited, not according to the order of nature, but according to the gracious intention of the gift, and together with the body nourished also the soul, leading it unto faith. […]

For the people, after crossing the sea, and being carried about in the desert during forty years, although they were there nourished with divine supplies, nevertheless were more mindful of their belly and their gullet than of God. Thereupon the Lord, driven apart into desert places after baptism, showed, by maintaining a fast of forty days, that the man of God lives "not by bread alone," but "by the word of God; " and that temptations incident to fulness or immoderation of appetite are shattered by abstinence.

That is, together with Moses they were under the shadow of the cloud and together passed through the sea. For when they saw that he was the first to cross, then they too boldly went through the midst of the waters. Something similar occurs with …

The manna on which they fed was a type of Christ crucified, the bread which came down from heaven, which whoso eateth shall live forever. Their drink was a stream fetched from a rock which followed them in all their journeyings in the wilderness; and this rock was Christ, that is, in type and figure.

And were all baptized unto Moses,....

He resumes his former argument ( ch. viii. ), about eating things offered to idols; and shows that it was utterly inconsistent with true Christianity, that it was downright gross idolatry, to eat them as things offered to idols; it is having fellowship with devils, which cannot consist with having fellowship with God,

Christ is the pillar cloud that screens us from the heat of God's wrath. Christ as "the light of the world" is our "pillar of fire" to guide us in the darkness of the world. As the rock when smitten sent forth the waters, so Christ, having been once for all smitten, sends forth the waters of the Spirit.

And were all baptized - In regard to the meaning of the word “baptized,” see the note at Mat 3:6. We are not to suppose that the rite of baptism, as we understand it, was formally administered by Moses, or by any other person, to the Jews, for there is not the least evidence that any such rite was then known, and the very circumstances here referred to forbid such an interpretation. They were baptized “in the cloud” and “in the sea,” and this cannot be understood as a religious rite administered by the hand of man. It is to be remembered that the word “baptism” has two senses - the one referring to the application of water as a religious rite, in whatever mode it is done; and the other the sense of “dedicating, consecrating, initiating into,” or bringing under obligation to. And it is evidently in this latter sense that the word is used here, as denoting that they were devoted to Moses as a leader, they were brought under his laws, they became bound to obey him, they were placed under his protection and guidance by the miraculous interposition of God. This was done by the fact that their passing through the sea, and under the cloud, in this manner, brought them under the authority and direction of Moses as a leader, and was a public recognition of their being his followers, and being bound to obey his laws. Unto Moses - (εἰς eis). This is the same preposition which is used in the form of baptism prescribed in Mat 28:19. See the note at that place. It means that they were thus devoted or dedicated to Moses; they received and acknowledged him as their ruler and guide; they professed subjection to his laws, and were brought under his authority. […]