To fully understand the criticisms concerning necromancy and Catholicism, we need to understand the basis for the criticism. What usually gets cited in these cases is Deuteronomy 18:9-14, which tells us:
“There shall not be found among you anyone who burns his sons or daughters as an offering, anyone who practices divination, a soothsayer, or a charmer, or a medium, or a wizard, or a necromancer. For whoever does these things is an abomination to the Lord; and because of these abominable practices the Lord your God is driving them out before you. You shall be blameless before the Lord your God. For these nations, which you are about to dispossess, give heed to soothsayers and to diviners; but as for you, the Lord your God has not allowed you to do so.”
Because necromancy means communicating with the dead, people accuse Catholics of doing that when we pray to the saints. The question is, does the above passage from Deuteronomy truly apply to Catholics praying to the saints? Let us examine the biblical quote in light of the context of that particular passage. As we can see, what is being condemned in Deuteronomy are the occult practices of the various Canaanite pagan cultures. In term of necromancy, the Canaanites believed that a person could communicate with the spirits of people who had died, and that these spirits could provide secret knowledge (“Where is buried treasure located?”, “How can I conjure a lightning bolt to kill my enemies?”, “Is my spouse cheating on me?”, “What exactly was the golden light in Lost?” - that sort of thing).
The big concern in Deuteronomy was that the Jews were about to enter the Holy Land, and therefore they could be influenced by Canaanite occult practices (and end up replacing their traditional Jewish doctrines with pagan ones). In other words, the Jews may think that there was something to all this necromancy business because lots of pagans were doing it. Practicing necromancy involved many problems. First of all, instead of contacting the spirits of dead humans, you could end up contacting demons (who could deceive you and ruin your life). Plus there is the attitude of seeking guidance from dead spirits instead of seeking guidance from God and the Law of Moses. And there is also the prideful attitude of thinking that one is entitled to secret knowledge to begin with.
Having said all this, we can now see why the ancient custom of necromancy is not the same thing that is involved with Catholics praying to the saints in heaven. The saints are not dead, but are more alive than they ever were on earth. We do not communicate with the saints in heaven to gain secret knowledge or to get guidance apart from God. We understand that any intercession they do is done in conjunction with God (i.e., they can ask God to help us, and God can help us through them).
We have to also understand that there is a big difference between the concepts of practicing magic and practicing prayer. The magician decides what he wants in life and tries to do magic to make it happen. He believes that if he says the correct words and performs the correct rituals the spirits are forced to comply with his desires and fulfill his needs. A Christian, however, tells God what he wants through prayer, and then adopts the attitude of “God’s will be done.” And just as we can ask one another to pray for us, we can ask the saints in heaven to pray for us. The concept of Christian fellowship on earth is simply extended to include the saints in heaven, which makes sense if you consider that we are all one in the Body of Christ to begin with (heaven, earth and purgatory combined).
To all this, we can point out that if people on earth should not communicate with saints in heaven, I doubt if Jesus would have spoken to Moses and Elijah during his Transfiguration in full view of Peter, James and John.
And finally, the act of seeking the help of saints through prayer is a doctrine of our Faith, and therefore, as far as Catholics are concerned, it has a divine origin and likewise divine approval. To put this in a simpler way, we pray to the saints because God told us we can.
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