"We were buried with Him through baptism into death" - Romans 6:4
What does this mean??
The following are notes mostly from James Boice's commentary:
Bapto = dip or immerse for a second.
Baptizo = dip or immerse with result of permanent change of identity
In 1 Cor 10:1-2 - Israel was baptized into Moses, as they went through the sea. But they weren't immersed. The water would have been sprinkled on them from above, more likely :) (See also Ps 77:16-19 and this link)
In Gal 3:27 baptize also means change of identity, referencing our water baptism, which symbolizes that change
Baptism is about our union with Christ, our changed relation to sin and death, not necessarily about immersion/burial acting that out.