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The problem with baptizing someone against their will is, they could then carry the mark of remission of original sin with them into hell, where it would serve to their additional torment. Certainly their own, personal sins would not be forgiven because they had no desire to be contrite for those sins, for they did not want baptism.
But if the person is unconscious, it seems to me that it might be okay to use a conditional form, in the event that they do want to be baptized. For they might have changed their mind when they lost consciousness. That would be, "I conditionally baptize thee (or 'you' -- insert name) in the Name of the Father and of the Son and of the Holy Ghost." You must say the words and pour the water at the same time. Someone else can't be the one pouring the water. The water has to run over the skin for each of the 3 divine Persons.
But there is a responsibility here -- you would have to stick around to be sure that if the person comes to, he or she would then need to be told that they were conditionally baptized, and after you explain all that to them, then stay nearby to supply them with any answers to their questions they might have. So it's not a light matter. You could become responsible to teach them the Faith from that day forward. So it's not just a game or something.
In this case, the "conditionally" refers to the possibility that the unconscious, dying person does want to be baptized, but didn't make that known for whatever reason. If he (or she) did NOT want baptism, then the conditional sacrament would not be effective, most tragically.
Can you imagine the scandal of being that close to heaven and losing it like that?
The DESIRE FOR BAPTISM is a very important thing. It is really a signal grace of predestination. Any priest on a battle field faces this dilemma. He would have no idea if all the dead soldiers lying there had been baptized or wanted to be or had changed their mind at the last moment. So his standard form would be the Conditional Baptism, since he can't know all the particulars, and there are so many victims to help all at once. The mere sight of a priest doing that should be enough to convert any observers, and if not, it would be to their serious culpability.
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