By being under the cloud and passing through the sea, the Israelites were baptized into Moses.
This is a short way of saying that they were baptized in the name of Moses (see also Romans 6:3; Galatians 3:27). Moses was God’s agent of salvation, and the Israelites were saved by being joined to him.
The salvation that God gave through Moses became the archetype of salvation in the Old Testament. In many ways, this deed of salvation foreshadowed the salvation that would be brought by Christ.
2 and all were baptized into Moses in the cloud and in the sea,