Well of course, you have to obey God. If you believe in God, you will do what he says. Protestants practice baptism. We obey Jesus because we go throughout the world baptizing those who believe.
The original poster is saying that by simply believing that baptism is a symbol, we are denying the power of God and are blaspheming Him. So, because Protestants obey God by being baptized but we don't share the particular theological fine print of Catholics, we are damned. Really?
It is in Scripture. Do you believe the Word of God or not?
Mark 16:16 He that believeth and is baptized shall be saved; but he that believeth not shall be damned.
Do you believe that your sins are washed away in Baptism or not?
Acts 22:16 And now why tarriest thou? arise, and be baptized, and wash away thy sins, calling on the name of the Lord.
They blaspheme the Spirit of God who claim that God can't wash away their sins by the pouring of water.