Dating old testament
Each is in some degree the beneficiary of the spiritual activities of the others, of their prayers and good works, their merits and satisfactions; nor is this degree to be wholly measured by those indirect ways in which the law of solidarity works out in other cases, nor by the conscious and explicit altruistic intentions of individual agents.It is wider than this, and extends to the bounds of the mysterious.Catholic teaching regarding prayers for the dead is bound up inseparably with the doctrine of purgatory and the more general doctrine of the communion of the saints, which is an article of the Apostle's Creed. XXV), "that purgatory exists, and that the souls detained therein are helped by the suffrages of the faithful, but especially by the acceptable sacrifice of the altar", is merely a restatement in brief of the traditional teaching which had already been embodied in more than one authoritative formula as in the creed prescribed for converted Waldenses by Innocent III in 1210 (Denzinger, Enchiridion, n.3 73) and more fully in the profession of faith accepted for the Greeks by Michael Palaeologus at the Second Ecumenical Council of Florence in 1439: "[We define] likewise, that if the truly penitent die in the love of God, before they have made satisfaction by worthy fruits of penance for their sins of commission and omission, their souls are purified by purgatorial pains after death; and that for relief from these pains they are benefitted by the suffrages of the faithful in this life, that is, by Masses, prayers, and almsgiving, and by the other offices of piety usually performed by the faithful for one another according to the practice  of the Church" (ibid., n. Hence, under "suffrages" for the dead, which are defined to be legitimate and efficacious, are included not only formal supplications, but every kind of pious work that may be offered for the spiritual benefit of others, and it is in this comprehensive sense that we speak of prayers in the present article.
For our own consolation as well as for theirs we want to believe in this living intercourse of charity with our dead.
When Judas and his men came to take away for burial the bodies of their brethren who had fallen in the battle against Gorgias, "they found under the coats of the slain some of the donaries of the idols of Jamnia, which the law forbiddeth to the Jews: so that all plainly saw, that for this cause they were slain.