2 Maccabees 12:42-46 tells about the Jew's prayers for the dead, the basis for that practice among the Catholics. 2 Maccabees was present in the Septuagint, the Bible of the early Christians. If that was present in the Septuagint, it was, then, why didn't the early Christians believe it (see 2 Cor. 6:2, KJV)? Just asking a sincere question.