What shall we say then? Are we to continue in sin that grace may abound? By no means! How can we who died to sin still live in it? Do you not know that all of us who have been baptized into Christ Jesus were baptized into his death? We were buried therefore with him by baptism into death, in order that, just as Christ was raised from the dead by the glory of the Father, we too might walk in newness of life.
For if we have been united with him in a death like his, we shall certainly be united with him in a resurrection like his. We know that our old self was crucified with him in order that the body of sin might be brought to nothing, so that we would no longer be enslaved to sin. For one who has died has been set free from sin. Now if we have died with Christ, we believe that we will also live with him. We know that Christ, being raised from the dead, will never die again; death no longer has dominion over him. For the death he died he died to sin, once for all, but the life he lives he lives to God. So you also must consider yourselves dead to sin and alive to God in Christ Jesus.
Let not sin therefore reign in your mortal body, to make you obey its passions. Do not present your members to sin as instruments for unrighteousness, but present yourselves to God as those who have been brought from death to life, and your members to God as instruments for righteousness. For sin will have no dominion over you, since you are not under law but under grace.
(Romans 6:1-14 ESV)
Some Reformed Theologians, (though not the Reformers themselves), will say that Romans 6, (and some other texts I could cite), are really not references to water baptism at all, but to an unmediated ‘spiritual’ baptism that takes place apart from any outward means, ritual or ceremony. The baptism mentioned here is not water baptism, but spiritual baptism. There are some things I think are wrong with that view.
First, this simply illogical. This is a good example of the logical fallacy called "Special Pleading." All that means is, they are saying this is a "special case" or an exception to the rule, without any valid reason for doing so. They don't do a good enough job proving why this case is special. Why shouldn't it say what it seems to be saying on the surface? The text seems to say that in baptism God promises that believers are united to the crucified, buried, and risen Christ, and that reflecting on this is a major source of sanctification in the life of the believer. Those that say that this use of the word "baptism" isn't referring to water baptism like it normally does, is simply not good reasoning, and not logical.
There is also a bit of preconceived bias in this. Tradition rears it's ugly head. Some say, "It can't mean water Baptism. That doesn't fit into my theology, so it must mean something else. This must be the exception to the rule that baptism refers to water baptism." So really, you've excluded any possibility of the Bible actually saying this at all. This is eisegesis. Reading your theology into the text because what the text actually says is uncomfortable to you.
That leads to the second objection I have. The Bible says there is only one baptism (Eph. 4:5), so splitting baptism up into a physical baptism and a spiritual baptism is illegitimate. In the first sermon ever preached, Peter says that those who are baptised receive the Holy Spirit (Acts 2:38). Paul says in 1 Cor. 12:13 that we were baptised into the body by the Spirit. Baptism and the working of the Holy Spirit are directly and clearly linked in the scriptures. True, baptism isn't the only possible way one may receive the Spirit, but you can't deny that it is a way.
This leads to my third objection. The Spirit does not work immediately or unmediated. This is the error of the Mystics and Charismatics. The Spirit always uses means. This is what we call "the means of grace". Because of our weakness and frailty, God has condescended and uses things of this world as pipes to communicate Himself to us. Means of grace are visible, external things which God uses to communicate Christ to us. The primary means of grace is the Word. An illustration may help here.
The book of Numbers recounts a time during their wilderness trek when the Israelites were disobedient to the Lord. So the Lord sent poisonous snakes into the camp. When the Israelites were bitten by snakes, God told Moses to make a copper serpent and put it on a pole. He then promised all who would look at the pole would be healed. How did a snake on a stick do such great things? It wasn't the snake on the stick. It wasn't looking at the snake on the stick. It was faith in the promises of God. It was faith that God would make good on his Word. It was a trust that when God said that those who looked at the copper serpant would be healed, he wasn't lying. Would you say to an Israelite, "By looking at the copper snake you are trusting in a created thing to heal you instead of God." God uses means. God promises to do great and wonderful things through the agency of creatures, and he makes good on his promises.
"So faith comes from hearing, and hearing through the Word of Christ." (Romans 10:17) "You have been born again, not of perishable seed but of imperishable, through the living and abiding Word of God." (1 Peter 1:23) I would agree with Augustine, who called the sacraments, “God’s visible words." Christ is the incarnate Word. The Bible is God's written Word. The Gospel is God's preached Word. The sacraments (including Baptism), are God's visible Word. We have no problem with God the Holy Spirit using a sermon or the preaching of the Gospel to save someone do we? Is the preaching of the Gospel only a picture that doesn't do anything? No! Does God truly offer Christ in the preaching of the Gospel? Yes. Do we thus conclude that everyone who hears the preaching of the Gospel is saved? Not at all, and we don't diminish the working of the Spirit in and through the Word either. Baptism works no differently then the preaching of the Gospel.
So don't misunderstand me. Just because you got wet, doesn't mean you're saved, or that these things are true about you. Baptism itself doesn't do anything. God is the one who performs these things. If you don't believe God, or trust in his promises, then you make God out to be a liar, and the water will just be a water of judgment.
In him also you were circumcised with a circumcision made without hands, by putting off the body of the flesh, by the circumcision of Christ, having been buried with him in baptism, in which you were also raised with him through faith in the powerful working of God, who raised him from the dead.
(Colossians 2:11-12 ESV)