http://catholicism.about.com/od/thesaints/f/Pray_to_Saints.htm
Question: Why Do Roman Catholics Pray to Saints?
Like all Christians, Catholics believe in life after death, but they also believe that our relationship with other Christians does not end with death. Catholic prayer to saints is a recognition of this communion.
Do Catholics believe that saints should be worshiped?
Why do they pray to saints?
Is there a difference between prayer and worship?
Answer:
The Communion of Saints
Like all Christians, Catholics believe in life after death. Those who have lived good lives and died in the faith of Christ will, as the Bible tells us, share in his resurrection.
While we live together on earth as Christians, we are in communion, or unity, with one another. But that communion doesn’t end when one of us dies. We believe that Christians in heaven, the saints, remain in communion with those of us on earth.
So, just as we might ask a friend or family member to pray for us, we can approach a saint with our prayers, too.
The Difference Between Prayer and Worship
Many non-Catholic Christians believe that it is wrong to pray to the saints, claiming that our prayers should be directed to God alone. Some Catholics, responding to this criticism, have argued that we do not pray to the saints but with them.
Both groups, however, are confusing prayer with worship. True worship (as opposed to veneration or honor) does indeed belong to God alone, and we should never worship man or any other creature as we worship God. But while worship may take the form of prayer, as in the Mass and other liturgies of the Church, not all prayer is worship. When we pray to the saints, we’re simply asking them to help us, by praying to God on our behalf, or thanking them for having already done so.
Prayers of the Saints : More Biblical Support
The Bible shows us how the prayers of others are very beneficial for us and that we should ask for their prayers.
In Genesis God tells Abimelech that he is to return Sarah to Abraham and how because of Abraham’s prayers Abimelech will be saved.
Genesis 20:7
“Therefore, return the man’s wife—as a spokesman he will intercede for you—that your life may be saved.”
Also, in Job we see God telling Job’s false friends Eliphaz and Temanite that they are to go to Job and ask for Job’s prayers. God tells them that he will accept Job’s prayers on their behalf.
Job 42:7-9
“ … the LORD said to Eliphaz the Temanite, ‘I am angry with you and with your two friends; for you have not spoken rightly concerning me, as has my servant Job. Now, therefore, take seven bullocks and seven rams, and go to my servant Job, and offer up a holocaust for yourselves; and let my servant Job pray for you; for his prayer I will accept, not to punish you severely. For you have not spoken rightly concerning me, as has my servant Job.’ Then Eliphaz the Temanite, and Bildad the Shuhite, and Zophar the Naamathite, went and did as the LORD had commanded them. And the LORD accepted the intercession of Job.”
Again in First Kings we see how King Jeroboam appeals for the intercession of a prophet, a man of God, who intercedes for him.
1 Kings 13:4-6
“ … King Jeroboam … stretched forth his hand from the altar … But the hand he stretched forth against him withered, so that he could not draw it back. … Then the king appealed to the man of God. ‘Entreat the LORD, your God,’ he said, ‘and intercede for me that I may be able to withdraw my hand.’ So the man of God entreated the LORD, and the king recovered the normal use of his hand.”
God did not create a me and Jesus only type of arrangement for our salvation. God works through others and God wants us to recognize others seek their help since it is nothing less than God’s help that comes through them. See Acts 9:4
1 Corinthians 16:18
“… for they refreshed my spirit as well as yours. So give recognition to such people.”
And we also see this Biblical encouragement to ask for others prayers made in the New Testament.
Romans 15:30-32
“I urge you, (brothers,) by our Lord Jesus Christ and by the love of the Spirit, to join me in the struggle by your prayers to God on my behalf, that I may be delivered from the disobedient in Judea, and that my ministry for Jerusalem may be acceptable to the holy ones …”
Also see Col 4:3; 1 Thess 5:25; Eph 6:18-19; 2 Thess 3:1
The prayer of others can be life giving.
1 John 5:16
“If anyone sees his brother sinning, if the sin is not deadly, he should pray to God and he will give him life.”
James 5:16
“ … The fervent prayer of a righteous person is very powerful.”
When the saints on earth die and go to heaven they are more righteous because they are even closer to God, and therefore they are even more open to the workings of God’s grace so that their prayers become even more efficacious for us. Asking for the prayers of others cannot violate Christ’s role as sole mediator, see Romans 15:30-32 above. We are all required to love one another and the Saints in heaven express their love for us by praying for us. We are all part of the ONE Body of Christ, 1 Corinthians 12:12-26. Although they have gone before us they are still connected to us through the head of Christ. It would be Scripturally wrong to say that we do not need them. See 1 Corinthians 12:21 below.
The ancient practice of asking the Saints in heaven to pray with us and for us goes back to the early church. The Bible shows that they are in heaven interceding on our behalf and taking our prayers up to God.
Revelation 5:8
“When he took it, the four living creatures and the twenty-four elders fell down before the Lamb. Each of the elders held a harp and gold bowls filled with incense, which are the prayers of the holy ones.”
Revelation 8:3-4
“And another angel came and stood at the altar with a golden censer; and he was given much incense to mingle with the prayers of all the saints upon the golden altar before the throne; and the smoke of the incense rose with the prayers of the saints from the hand of the angel before God.”
The Saints in heaven belong to the Body of Christ. And the Christians on earth also belong to the Body of Christ. So, we have the question, “How many Bodies does Christ have ?”
1 Corinthians 12:27
“Now you are Christ’s body, and individually parts of it.”
1 Corinthians 12:20
“But as it is, there are many parts, yet one body.”
Cf. Eph 4:4; Col 3:15
Therefore, the saints here on earth are united with the Saints in heaven in the one Body of Christ. We would be wrong to ignore the help that Jesus wants to give us through them and their intercession on our behalf.
James 5:16
“… pray for one another, that you may be healed. The fervent prayer of a righteous person is very powerful.”
We need the prayers of the Saints in Heaven because we are all one family, and part of following Jesus is being humble enough to accept that we need there help.
1 Corinthians 12:20-21
“But as it is, there are many parts, yet one body. The eye cannot say to the hand, ‘I do not need you,’ nor again the head to the feet, ‘I do not need you.’ ”
Therefore, it is a good and holy thing to avail ourselves of help that God wants to give to us through their intercession done in Jesus Christ.
From http://www.defendingthebride.com/ma3/only9.html
In doing so it's no different than those who inquire of spirits in a seance....or New Agers who speak with so called descended masters. Our God is a God of distinctions....HE draws lines we cannot nor should we seek to pass....this is one of them...and He's quite clear about that.