The Complete Jewish Bible records the teaching of the Apostle Paul in the 15th Chapter this way:
1 Now, brothers, I must remind you of the Good News which I proclaimed to you, and which you received, and on which you have taken your stand, 2 and by which you are being saved - provided you keep holding fast to the message I proclaimed to you. For if you don't, your trust will have been in vain. 3 For among the first things I passed on to you was what I also received, namely this: the Messiah died for our sins, in accordance with what the Tanakh says; 4 and he was buried; and he was raised on the third day, in accordance with what the Tanakh says; 5 and he was seen by Kefa, then by the Twelve; 6 and afterwards he was seen by more than five hundred brothers at one time, the majority of whom are still alive, though some have died. 7 Later he was seen by Ya'akov, then by all the emissaries; 8 and last of all he was seen by me, even though I was born at the wrong time. 9 For I am the least of all the emissaries, unfit to be called an emissary, because I persecuted the Messianic Community of God. 10 But by God's grace I am what I am, and his grace towards me was not in vain; on the contrary, I have worked harder than all of them, although it was not I but the grace of God with me. 11 Anyhow, whether I or they, this is what we proclaim, and this is what you believed. 12 But if it has been proclaimed that the Messiah has been raised from the dead, how is it that some of you are saying there is no such thing as a resurrection of the dead? 13 If there is no resurrection of the dead, then the Messiah has not been raised; 14 and if the Messiah has not been raised, then what we have proclaimed is in vain; also your trust is in vain; 15 furthermore, we are shown up as false witnesses for God in having testified that God raised up the Messiah, whom he did not raise if it is true that the dead are not raised. 16 For if the dead are not raised, then the Messiah has not been raised either; 17 and if the Messiah has not been raised, your trust is useless, and you are still in your sins. 18 Also, if this is the case, those who died in union with the Messiah are lost. 19 If it is only for this life that we have put our hope in the Messiah, we are more pitiable than anyone. 20 But the fact is that the Messiah has been raised from the dead, the firstfruits of those who have died. 21 For since death came through a man, also the resurrection of the dead has come through a man. 22 For just as in connection with Adam all die, so in connection with the Messiah all will be made alive. 23 But each in his own order: the Messiah is the firstfruits; then those who belong to the Messiah, at the time of his coming; 24 then the culmination, when he hands over the Kingdom to God the Father, after having put an end to every rulership, yes, to every authority and power. 25 For he has to rule until he puts all his enemies under his feet. 26 The last enemy to be done away with will be death, 27 for "He put everything in subjection under his feet."m But when it says that "everything" has been subjected, obviously the word does not include God, who is himself the one subjecting everything to the Messiah. 28 Now when everything has been subjected to the Son, then he will subject himself to God, who subjected everything to him; so that God may be everything in everyone. 29 Were it otherwise, what would the people accomplish who are immersed on behalf of the dead? If the dead are not actually raised, why are people immersed for them? 30 For that matter, we ourselves - why do we keep facing danger hour by hour? 31 Brothers, by the right to be proud which the Messiah Yeshua our Lord gives me, I solemnly tell you that I die every day. 32 If my fighting with "wild beasts" in Ephesus was done merely on a human basis, what do I gain by it? If dead people are not raised, we might as well live by the saying, "Let's eat and drink, for tomorrow we die!" 33 Don't be fooled. "Bad company ruins good character." 34 Come to your senses! Live righteously and stop sinning! There are some people who lack knowledge of God - I say this to your shame.
Reading through this, it seems to me that this translation contradicts your statement. I should clarify that it contradicts in that while yes, he is speaking of ressurection, he is not separating himself from those who are immersed for the dead. He does not appear to be discounting their act at all, rather justifying it. Now, this is just how I am reading it of course..........so............