1 Cor. 10:1-5 (ESV)
I want you to know, brothers, that our fathers were all under the cloud, and all passed through the sea,  and all were baptized into Moses in the cloud and in the sea,  and all ate the same spiritual food,  and all drank the same spiritual drink. For they drank from the spiritual Rock that followed them, and the Rock was Christ.  Nevertheless, with most of them God was not pleased, for they were overthrown in the wilderness.
I marvel at the agility with which Paul correlates the Exodus to the Christian sacramental life. There is a lot of food for thought here. Some would say baptized means to be immersed. I don’t normally get in fights over that sort of thing. But I would like to bring out that no one is immersed into a cloud. And during the Exodus, the only people immersed in the sea were Pharaoh’s soldiers, the rest walked on dry ground. This by the way nullifies the whole thing about it being the reed sea at low tide, and not the red sea. If it was just a matter of a low tide it is hard to see how the ground would be dry, and the Pharaoh’s men would drown. I would also like to point out that there were many infants who passed through those waters through no choice of their own.
We Christians are on a journey, we are pilgrims. Our red sea was baptism. God sustains us on our journey to the promised land of heaven with Spiritual food and drink, his body and blood given for the forgiveness of sins, just as he gave the Israelites spiritual, and miraculous food (manna) and drink (the water from the Rock) in the desert. Here we find that Rock was Christ. I’m sure it looked like an ordinary Rock, and the water tasted felt and looked like ordinary water, but it was Christ. Paul could of said it symbolized Christ, or foreshadowed Christ, (the Greeks had words for symbolizing) but he didn’t. He used the word was, past tense for is.
Paul ends with a warning though. Many were overthrown in the wilderness. God was not pleased with most of them. The sacraments are double edged, both a blessing and a curse. We need be careful, and thoughtful, approaching the presence of God in with and under the bread and wine at the altar.