What does 1 Corinthians 10:4 mean?
Paul continues to make a connection between the Israelites who wandered in the wilderness and the Christians in Corinth. This concept applies equally well to all Christians. The Israelites were "baptized into Moses" through their experiences of the Lord's leading in the cloud (Exodus 13:21) and the Lord's protection as they went through the Red Sea (Exodus 14:21–28). In addition, they all ate the same spiritual food in the form of manna from heaven (Exodus 16:15).Here it is stated that they all drank the same spiritual drink in the form of the water that flowed miraculously from a rock (Exodus 17:1–7). Paul identifies that Rock as Christ Himself, providing water for the Israelites. This makes the connection between the Israelites and the Christians in Corinth even more obvious.
Like those Israelites, Christians are baptized, though into Christ instead of Moses. Christians observe communion by eating the spiritual food of Christ's body, rather than manna. They drink the spiritual drink of His blood, rather than water from the rock. It's possible that Paul's intention in this passage is to make a specific connection between the experiences of the Israelites and the Corinthians' practice of Christian baptism and communion.