Isn’t h2o water baptism a work of the flesh?
No - it is merely compliance or obedience.
If we say that we believe in the gospel and believe in Jesus Christ as our Lord and Master then as disciples we need to submit
to our Lord's teachings and to his commandments ... one of which is most definitely water baptism by full immersion.
Faith in scripture and belief in scripture - sola scriptura - means to read and
do the word of God > to act on it.
Even Jesus himself underwent water baptism to demonstrate to us all the absolute importance of this sacrament.
Then Jesus came from Galilee to the Jordan to John, to be baptized by him.
Matthew 3:13 (ESV)
15 “If you love me, you will keep my commandments.
21 Whoever has my commandments and keeps them, he it is who loves me. And he who loves me will be loved by my Father,
and I will love him and manifest myself to him.
John 14: (ESV)
If you keep my commandments, you will abide in my love, just as I have kept my Father's commandments and abide in his love.
John 15:10 (ESV)
47 “Can anyone withhold water for baptizing these people, who have received the Holy Spirit just as we have?”
48 And he commanded them to be baptized in the name of Jesus Christ. Then they asked him to remain for some days.
Acts 10: (ESV)