Hello Rvt,
PrayRosary puts it best "In the second Book of Machabees it is narrated that after Judas had defeated Gorgias, he came with his company to bury the Jews slain in the battle. "Making a gathering, he sent twelve drachmas of silver to Jerusalem for sacrifice to be offered for the sins of the dead." He did not regard their sins to be grievous, "because he considered that they who had fallen asleep with godliness had great grace laid up for them." The sacred writer then expresses the doctrine involved herein: "It is, therefore, a holy and wholesome thought to pray for the dead, that they maybe loosed from their sins." (12:43-46)." I'm going to provide you with a few more links to read, let me know if you have any other questions.
http://www.americancatholic.org/Messenger/Nov2000/Wiseman.asp
http://www.newadvent.org/cathen/04653a.htm
http://www.ctsp.co.il/prayer_dead.htm
Chase
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