Okay, I don't want to stir up trouble here, but I really disagree with you on this point, and so does the scripture--even the apostle Paul, which you quoted. Read Romans 6 for a nice view of what Paul thought of the work and importance of baptism.

I'd like to take a look at some of the scripture that you cited. I fear that you are, sadly, taking some of them out of context.
Acts 16:29-31: To put this scripture in it's proper light, let's go ahead and read on to verse 34. It is interesting to note that the verse you ended with showed Paul instructing them to "Believe in the Lord Jesus" to be saved, and then in verse 33, after Paul had preached the gospel of Jesus to him and his household, they were baptized. And in verse 34 it says that he "rejoiced greatly, having believed in God with his whole household." You see, baptism and belief are so closely intertwined in the scripture that it is almost impossible to separate them in matters of conversion. In Mark 16:16 Jesus himself said "he that believes and is baptized will be saved, he that doesn't believe will be condemned." You could almost say that Jesus treated baptism as a part of belief in this scripture. The same is true in the scripture in Acts. Paul preached. They believed and were baptized. Oh, and after Christ's ascension on the day of Pentecost when Peter preached the first gospel sermon, he too was asked what to do to be saved. His reply: "Repent and be baptized, every one of you, for the remission of sins". Very similar situation except Peter had already preached Jesus to them when they asked him what to do to be saved.

Ephesians 6:19 speaks of no "new gospel". Perhaps you meant the"mystery of the gospel" for which Paul is seeking boldness to preach. But in any case, Paul was soliciting prayers, not giving a new teaching. It wouldn't really have been fair for him to ask for boldness to preach something he hadn't already preached to them.

1 Corinthians 3:10 is talking about the nature of ministry, not the nature of the gospel. You see, Paul was dealing with some divisions that had come up among the Corinthian brothers and sisters. People were beginning to take pride in who had baptized/converted them. They were naming each group after the one who had performed the baptism. Therefore, Paul, in 1 Corinthians 1:14:15, thanked God that no one there had the opportunity to say they were baptized in his name. Consequently, in chapter 3 he sets forth the idea that ministry often takes place in steps. One man may preach the gospel to someone while another man may come along and reinforce that preaching and/or convert that person.

You mentioned another scripture. I'd like to see it.

Ephesians 2:8-9, Titus 3:5: These verses are commonly interpreted to mean something they don't say. They do say that one is saved by grace, not by works. However, they do not classify baptism as a work. Nowhere in the scripture is baptism considered a work. And if it is considered logically, baptism really isn't a "work" beyond it's classification as a physical act. Baptism is a symbolic act of faith. It is not the "work" of baptism that saves anyone, but the grace of God--which, consequently, was the sacrifice of his Son which afforded the forgiveness of sins--with which baptism brings us into contact(1 Peter 3:21). We join with him in the sacrifice of his life (Romans 6:3-5) so that we can also join with him in his ressurection.

Romans 10:9-10: I'll deal with this scripture seperately, as it is not dealing with the same topic as the other two scriptures with which you classified it. The first thing I want to point out is the Paul says that those who believe "will be saved". Note that this does not say "are saved". There is a stark difference. In the following verses we find that it is confession, not belief, that brings about salvation. This brings me to my second observation: confession is a work to the same degree that baptism is a work. So, is confession a "work", which Paul plainly states can't save us, or is baptism a part of our belief response? You see, Peter does say that baptism saves(1 Peter 3:21), and it is he that Jesus said would open the doors to the kingdom(Matthew 16:18-19), not Paul. I'm not saying that Paul is wrong, but I am saying that Paul's gospel did not differ from that of the other apostles as it was all based on the life and teaching of Jesus. Paul's writings, you see, are not the entirety of the revealed will of God. What was the gospel? Paul told us very plainly what the gospel is:
1 Corinthians 15:1-4
Now I make known to you, brethren, the gospel which I preached to you, which also you received, in which also you stand, by which also you are saved, if you hold fast the word which I preached to you, unless you believed in vain. For I delivered to you as of first importance what I also received, that Christ died for our sins according to the Scriptures, and that He was buried, and that He was raised on the third day according to the Scriptures...

So, seeing that Paul said the gospel (of grace, if you will) is the death burial and resurrection of Christ, evidenced by his appearances which are described in the following verses and that it is the gospel that saves, how then can be take advantage of it? Well, one of the ways we MUST take advantage of it is baptism. Repentence and confession are also requirements. Not requirements made up by the any church. Not requirements done away with by Paul. No, these requirements were set forth by Christ and the Holy Spirit taught them to and brought them to the remembrance of the apostles who preached them(John 14:26).

What else did Paul say about baptism? Well, Galatians 3:27 might shed some light. In this scripture Paul tells us that if we are baptized into Christ we put on Christ. You're right about one thing. Baptism doesn't put Christ into us. We must do that for ourselves. But putting us into Christ is a whole different matter entirely. As far as I can read, baptism is the only thing mentioned in the bible that will do that.

Shandar

P.S. I've been writing this for about 5 days now. Forgive me if I've been a little distracted.