One of many strange teachings of Catholicism is prayer to the Saints, or otherwise asking the saints to pray for you. Is this a Biblical practice? Not even remotely. The Bible makes the Lord's opinion on talking to the dead perfectly clear, and He is far from friendly to the idea.
In the law of Moses, the Lord condemns a range of occultic practices, among which was inquiring of the dead (Deuteronomy 18:10-12). This practice was so detestable to the Lord that He even says it is this for which He was driving the Canaanites out of the land, meaning this was not just a piece of the Mosaic covenant. Unlike food laws, which would be specifically revoked in the New Testament, this is a moral law, like the law against murder. It is applicable to all people at all times.
This would include Saul, who consulted the Witch of En Dor (1 Samuel 28:9-20) to bring up Samuel. Unlike any other time in the Bible, and seemingly any other time in the witch's life based on her surprise, the Bible tells us that Saul did successfully raise Samuel. His response was less than favourable. He was upset about being disturbed (v15). Saul told him that he was distressed, as the Lord had left, and wanted to know what to do. Samuel rebuked him, basically saying there is no point asking Samuel when the Lord had already spoken (v16-19). Furthermore, for going to Samuel instead of the Lord, 1 Chronicles 10:13-14 tells us that Saul died.
Isaiah repeats the same principle. "And when they say to you, “Seek those who are mediums and wizards, who whisper and mutter,” should not a people seek their God? Should they seek the dead on behalf of the living? To the law and to the testimony! If they do not speak according to this word, it is because there is no light in them." (Isaiah 8:19-20). By Isaiah's words, would we not be justified to say that Catholics, who do seek the dead on behalf of the living ("Holy Mary, Mother of God, pray for us sinners, now and at the hour of our death") have no light in them, because they do not speak according to this word?
Even if Catholics argue that they are merely seeking the saints (which, by the way, they cannot always guarantee are even in Heaven) because they believe these people have a more direct access to God, not because they expect a direct answer themselves, this is still an abomination. The Bible tells us that there is one mediator between God and man, that being Jesus Christ (1 Timothy 2:5). Even our own weakness, our failures to know what to pray for, are translated by the Holy Spirit (Romans 8:26). Furthermore, we are told to come boldly before the throne of grace (Hebrews 4:16). So where is the logic in dodging our mediator, foregoing the use of our interpreter, and sending someone whom we cannot even guarantee will hear us before the throne of grace? Let's repeat the words of Isaiah: "should not a people seek their God? Should they seek the dead on behalf of the living?" And this even before the curtain was torn in two! How much more can we, who have been purchased by His precious blood, consult with Jesus personally? There is no more direct access to God than through praying to Him.
Even without the Bible, God's omnipresence, omnipotence, and omniscience alone should tell us that it is far better to pray to Him. He is omnipresent, allowing Him to hear every prayer at once. He is omnipotent, allowing Him to grant any prayer He desires in any way He sees fit. He is omniscient, so there is no one more qualified than Him to know the best way to answer prayer. What logic is there in consulting a human, much less a dead one, who has none of these attributes, over God? Both logic and the word tell us that the concept of talking to the saints, be it actual prayer, or a mere prayer request, is not Christian one. Catholics need to repent of this occultic practice, abandon the Church that teaches it, and serve the Lord who outright condemns it, but through His blood, sweat, and tears, gave everything in order to not have to condemn us.