Regarding 2 Macc 12:44-45, the surrounding verses make it clear that a resurrection from the dead is in mind here. This passage from Maccabees is not dealing with purgatory:
"For if he were not expecting that those who had fallen would rise again, it would have been superfluous and foolish to pray for the dead. But if he was looking to the splendid reward that is laid up for those who FALL ASLEEP in godliness, it was a holy and pious thought. Therefore he made atonement for the dead, so that they might be delivered from their sin" (2 Macc 12:44-45 RSV).
The Catholic NAB, in the footnote to 2 Macc 12:42-46, says:
"This is the earliest statement of the doctrine that prayers (v 42) and sacrifices (v 43) for the dead are beneficial. The statement is made here, however, only for the purpose of proving that Judas believed in the resurrection of the just (2 Mc 7, 9, 14, 23, 36). That is, he believed that expiation could be made for certain sins of otherwise good men--soldiers who had given their lives for God's cause. Thus, they could share in the resurrection. His belief was similar to, but not quite the same as, the Catholic doctrine of purgatory."
Concerning 1 Cor 3:15, the New Jerusalem Bible notes:
"Purgatory is not directly envisaged here, but this text is one of those on the basis of which the Church has made this doctrine explicit."
"While interpreters (particularly Roman Catholics) of another era attempted occasionally to relate these verses to purgatory, almost no scholar working today would make that connection, regardless of confessional persuasion or background" (Marion Soards, 1 Corinthians, p. 78).
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