There are some that say that there is but one life. They cannot be Christian. There are others who say that the protestants, particularly the reformed are ignorant of tradition. They are wrong.
In the church, the baptism of the dead is treated as a gross superstition, and there is a very long quote by Calvin below the bar that summarizes this

 1 CORINTHIANS 15:12-29

¹²Now if Christ is proclaimed as raised from the dead, how can some of you say there is no resurrection of the dead?¹³If there is no resurrection of the dead, then Christ has not been raised; ¹⁴and if Christ has not been raised, then our proclamation has been in vain and your faith has been in vain. ¹⁵We are even found to be misrepresenting God, because we testified of God that he raised Christ — whom he did not raise if it is true that the dead are not raised. ¹⁶For if the dead are not raised, then Christ has not been raised. ¹⁷If Christ has not been raised, your faith is futile and you are still in your sins. ¹⁸Then those also who have died in Christ have perished. ¹⁹If for this life only we have hoped in Christ, we are of all people most to be pitied.

²⁰But in fact Christ has been raised from the dead, the first fruits of those who have died. ²¹For since death came through a human being, the resurrection of the dead has also come through a human being; ²²for as all die in Adam, so all will be made alive in Christ. ²³But each in his own order: Christ the first fruits, then at his coming those who belong to Christ. ²⁴Then comes the end, when he hands over the kingdom to God the Father, after he has destroyed every ruler and every authority and power. ²⁵For he must reign until he has put all his enemies under his feet. ²⁶The last enemy to be destroyed is death. ²⁷For “God has put all things in subjection under his feet.” But when it says, “All things are put in subjection,” it is plain that this does not include the one who put all things in subjection under him. ²⁸When all things are subjected to him, then the Son himself will also be subjected to the one who put all things in subjection under him, so that God may be all in all.

²⁹Otherwise, what will those people do who receive baptism on behalf of the dead? If the dead are not raised at all, why are people baptized on their behalf?

I am going to leave verse 29 for Calvin: he knew his theology, and his discussion of the scholarly effort to understand this verse is masterful. (Or, I will leave the Mormons to a dead Frenchman. He would destroy them in a debate).

I want to consider the liberal error. The resurrection is a myth. Christ is but a symbol. It is a metaphor: Christ is the Tao, the Buddha — the good and proper way. Karen Armstrong flirts with this when she talks about human evolution moving to new levels of spirituality at around the beginning in the Iron Age — putting Buddha and Christ and Lao on the same page, as they emerged at (in her view) roughly the same period of time.

However, this misses the point. If Christ did not rise, we are left at best with a form of stoicism, or worshipping our emotions. The resurrection of Christ is fundamental. It cannot be smoothed over with biography, experience, or rhetoric from some lapsed nun, or compromising cleric.

Either Christ is risen or he has not. We either have hope or we do not. It is fundamental to our faith: and the Buddha was honest enough to not offer such hope, nor was the Ta’o, nor the rabbis, nor the Stoics and Neoplatonists or Confucians.

The hope of salvation in Christendom comes from Christ’s resurrection, and only psychopathic bastards like Mohammed, Joseph Smith, Jim Jones and L Ron Hubbard preach a lie, decieving many if not all, that there is any other way.

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This is Calvin on verse 29

Else what shall they do He resumes his enumeration of the absurdities, which follow from the error under which the Corinthians labored. He had set himself in the outset to do this, but he introduced instruction and consolation, by means of which he interrupted in some degree the thread of his discourse. To this he now returns. In the first place he brings forward this objection — that the baptism which those received who are already regarded as dead, will be of no avail if there is no resurrection. Before expounding this passage, it is of importance to set aside the common exposition, which rests upon the authority of the ancients, and is received with almost universal consent. Chrysostom, therefore, and Ambrose, who are followed by others, are of opinion that the Corinthians were accustomed, when any one had been deprived of baptism by sudden death, to substitute some living person in the place of the deceased — to be baptized at his grave. They at the same time do not deny that this custom was corrupt, and full of superstition, but they say that Paul, for the purpose of confuting the Corinthians, was contented with this single fact, “De ce seul argument;” — “With this single argument.” that while they denied that there was a resurrection, they in the mean time declared in this way that they believed in it. For my part, however, I cannot by any means be persuaded to believe this, “Mats ie ne voy rien qui me puisse amener a suyure ceste coniecture;” — “But I see nothing that could induce me to follow that conjecture.” for it is not to be credited, that those who denied that there was a resurrection had, along with others, made use of a custom of this sort. Paul then would have had immediately this reply made to him: “Why do you trouble us with that old wives’ superstition, which you do not yourself approve of?” Farther, if they had made use of it, they might very readily have replied: “If this has been hitherto practiced by us through mistake, rather let the mistake be corrected, than that it should have weight attached to it for proving a point of such importance.”

Granting, however, that the argument was conclusive, can we suppose that, if such a corruption as this had prevailed among the Corinthians, the Apostle, after reproving almost all their faults, would have been silent as to this one? He has censured above some practices that are not of so great moment. He has not scrupled to give directions as to women’s having the head covered, and other things of that nature. Their corrupt administration of the Supper he has not merely reproved, but has inveighed against it with the greatest keenness. Would he in the meantime have uttered not a single word in reference to such a base profanation of baptism, which was a much more grievous fault? He has inveighed with great vehemence against those who, by frequenting the banquets of the Gentiles, silently countenanced their superstitions. Would he have suffered this horrible superstition of the Gentiles to be openly carried on in the Church itself under the name of sacred baptism? But granting that he might have been silent, what shall we say when he expressly makes mention of it? Is it, I pray you, a likely thing that the Apostle would bring forward in the shape of an argument a sacrilege “Ce sacrilege horrible;” — “This horrible sacrilege.” by which baptism was polluted, and converted into a mere magical abuse, and yet not say even one word in condemnation of the fault? When he is treating of matters that are not of the highest importance, he introduces nevertheless this parenthesis, that he speaks as a man. (Romans 3:5; Romans 6:19; Galatians 3:15.) Would not this have been a more befitting and suitable place for such a parenthesis? Now from his making mention of such a thing without any word of reproof, who would not understand it to be a thing that was allowed? For my part, I assuredly understand him to speak here of the right use of baptism, and not of an abuse of it of that nature.

Let us now inquire as to the meaning. At one time I was of opinion, that Paul here pointed out the universal design of baptism, for the advantage of baptism is not confined to this life; but on considering the words afterwards with greater care, I perceived that Paul here points out something peculiar. For he does not speak of all when he says, What shall they do, who are baptized? etc. Besides, I am not fond of interpretations, that are more ingenious than solid. What then? I say, that those are baptized for dead, who are looked upon as already dead, and who have altogether despaired of life; and in this way the particle ???? will have the force of the Latin pro, as when we say, habere pro derelicto; — to reckon as abandoned The form of expression referred to is made use of by Cicero. (Art. 8.1.) Or if you would prefer another signification, to be baptized for the dead will mean — to be baptized so as to profit the dead — not the living, “Proufite apres la mort, et non pas la vie durant;” — “Profits after death, and not during life.” Now it is well known, that from the very commencement of the Church, those who had, while yet catechumens, “Estans encore sur la premiere instruction de la doctrine Chrestienne;” — “Being as yet in the first rudiments of Christian doctrine.” fallen into disease, “Quelque maladie dangereuse;” — “Some dangerous malady.” if their life was manifestly in danger, were accustomed to ask baptism, that they might not leave this world before they had made a profession of Christianity; and this, in order that they might carry with them the seal of their salvation.

It appears from the writings of the Fathers, that as to this matter, also, there crept in afterwards a superstition, for they inveigh against those who delayed baptism till the time of their death, that, being once for all purged from all their sins, they might in this state meet the judgment of God.

A gross error truly, which proceeded partly from great ignorance, and partly from hypocrisy! Paul, however, here simply mentions a custom that was sacred, and in accordance with the Divine institution — that if a catechumen, who had already in his heart embraced the Christian faith, “Si celuy qui n’ estoit pas encore parfaitement instruit en la doctrine Chrestienne, et toutesfois auoit desia de vraye affection embrasse la foy;” — “If one, that had not as yet been fully instructed in Christian doctrine, but yet had already embraced the faith with true affection.” saw that death was impending over him, he asked baptism, partly for his own consolation, and partly with a view to the edification of his brethren. For it is no small consolation to carry the token of his salvation sealed in his body. There is also an edification, not to be lost sight of — that of making a confession of his faith. They were, then, baptized for the dead, inasmuch as it could not be of any service to them in this world, and the very occasion of their asking baptism was that they despaired of life. We now see that it is not without good reason that Paul asks, what they would do if there remained no hope after death?