I keep hearing the argument that "be baptized" is in the passive voice, and this somehow means that it is not something we do. An imperative has an implied "you" in front of it. We just don't say the "you," but the idea is that "you" are the one being commanded to obey the imperative. Certainly, we are not baptizing ourselves, but the command is given to those to whom the gospel is preached in order to command them to allow the apostles to baptize them. So the command demands obedience on the part of the listener. Hence, the command is "(You) be baptized," implying that you are doing something, not because you are baptizing yourself but because you are letting others baptize you.
Notice that the same argument is not used of the imperative "believe." Does that mean these same people believe that we do the believing? Not usually, as this tends to be an argument that only God gives these without our doing them in response to what God does. Yet, if we are going to take this grammatical argument consistently, it must mean that we do the believing, since the voice is active.
But one cannot establish any of this from the voice of a verb. This line of argumentation is simply a misunderstanding. If one says, "Let your mind be changed," someone else may or may not be doing the changing, but the command to let it happen must be obeyed by you, as you are in control of your mind. If someone says, "Be filled with food," although this is passive, it is doubtful that someone else is spoon-feeding you. Instead, what is filling you is food, but you are likely the one putting it into your body. In other words, even though the commands are in the passive voice, indicating that someone or something is acting upon you, you are being commanded to do something. You are the one who allows one to baptize you, allows your mind to be changed, allows food to fill you, etc. You are actively letting someone or something do something to you.
My point is that no one ever argued that people baptize themselves. What they are being called to do is commit themselves to Christ by letting His ambassadors baptize you into His Church. It is equivalent to saying, "Let us make you a disciple of Christ." We know that the ones who are doing the active work of baptism are the apostles, since they are the ones in the context who actively baptize people with water. The command is simply to let them do it. The other commands in parallel to it, like "believe on the Lord Jesus Christ," "turn to God," "repent," are all in the active voice. If a passive voice means one is passive in the activity described then one has to argue that an active voice means one is active in the activity being described. This isn't completely false, but it is in the way these proponents of passive baptism use it because they want to say that God is doing everything in baptism and we do nothing. The problem is that one must then say that we do everything in believing, turning to God, and repenting and God does nothing because these commands and descriptions of people doing them are in the active voice.
No one is accurately going to be able to glean a biblical theology of baptism from grammatical voice. Instead, one needs to find support for his argument elsewhere.