Is baptism a work of man and thus unneeded?

Is baptism a work of man and thus unneeded? 
Ephesians 2:8-9 is great: "For by grace you have been saved through faith; and that not of yourselves, it is the gift of God;  not as a result of works, so that no one may boast." Without studying, people can take this too far. I've even heard it said that repentance can't be necessary, as it would invalidate the free gift of God. (So would a serial murderer be fine as long as he had faith alone?")

Q: From Eph 2:8-9, is baptism unnecessary because it is a work of man? 
A: "Having been buried with Him in baptism, in which you were also raised up with Him through faith in the working of God, who raised Him from the dead." (Col 2:12) 

Some like to say that anything that is a work cannot be a requirement for salvation. Baptism, along with other factors such as belief, "now saves you." (1 Pet 3:21) Is there something about being wet that does it? Something about our righteousness that we can brag about? Read Col 2:12 again, and the answer is "Nope!" Baptism is the working of God, not man. It's His designated operating table. 

"For God so loved the world that He gave His only begotten Son, that whoever believes in Him should not perish but have everlasting life." (Jn 3:16) "Jesus answered and said to them, "This is the work of God, that you believe in Him whom He has sent."" (Jn 6:29) 

These are great works, and they're absolutely necessary. 
(PN135)