Praying to Mary breaks a command:
Matthew 6
[SUP]9 [/SUP]After this manner therefore pray ye: Our Father which art in heaven, Hallowed be thy name.
The rosary completely perverts this command from Jesus on how to pray by giving Mary glory alongside God. Then after the rosary the prayer begins as:
HAIL, HOLY QUEEN, Mother of Mercy, our life, our sweetness and our hope! To thee do we cry, poor banished children of Eve; to thee do we send up our sighs, mourning and weeping in this vale of tears. Turn then, most gracious advocate, thine eyes of mercy toward us, and after this our exile, show unto us the blessed fruit of thy womb, Jesus. O clement, O loving, O sweet Virgin Mary!
This is blatant idolatry and Mary worship, and outright profanes Jesus' command to pray to the Father. It undermines his example and undermines scripture.
HAIL, HOLY QUEEN
Where does it ever say it's ok to pray to the dead? There are other examples of communicating with the dead:
Deuteronomy 18:9-12
When you come into the land that the Lord your God is giving you, you shall not learn to follow the abominable practices of those nations. There shall not be found among you anyone who burns his son or his daughter as an offering, anyone who practices divination or tells fortunes or interprets omens, or a sorcerer or a charmer or a medium or a necromancer or one who inquires of the dead, for whoever does these things is an abomination to the Lord. And because of these abominations the Lord your God is driving them out before you.
Isaiah 8
19 When someone tells you to consult mediums and spiritists, who whisper and mutter, should not a people inquire of their God? Why consult the dead on behalf of the living? 20 Consult God’s instruction and the testimony of warning. If anyone does not speak according to this word, they have no light of dawn. 21 Distressed and hungry, they will roam through the land; when they are famished, they will become enraged and, looking upward, will curse their king and their God. 22 Then they will look toward the earth and see only distress and darkness and fearful gloom, and they will be thrust into utter darkness.
Revelation 22
18 I warn everyone who hears the words of the prophecy of this scroll: If anyone adds anything to them, God will add to that person the plagues described in this scroll. 19 And if anyone takes words away from this scroll of prophecy, God will take away from that person any share in the tree of life and in the Holy City, which are described in this scroll.