First, the common objections:
Objection 1) "The Bible says there is only one mediator between God and man(1 Timothy 2:5)--that's Jesus, so we cannot pray to any saint!"
Here is the text they are referring to:
For there is one God, and one mediator of God and men, the man Christ Jesus: Who gave himself a redemption for all, a testimony in due times.--1 Timothy 2:5-6
he is mediator of a better covenant--Hebrews 8:6
Answer: This understanding is flawed. Prayer CAN be a form of worship, but does it necessarily have to be? Is it worship to ask God to heal aunt Sally? Certainly it is when the main purpose of their prayer is thanksgiving and glorifying God.
Objection 4) "The dead know nothing!" (Ecclesiastes 9:5) [soul sleep]
Answer: A favorite verse used by soul sleepers, they want to limit the verse to this section of the sentence. Here is the context of the verse:
For to him that is joined to all the living there is hope; for a living dog is better than a dead lion. For the living know that they shall die; but the dead know not any thing, neither have they any more a reward; for the memory of them is forgotten. --Ecclesiastes 9:4-5The first sentence says that "him that is joined to all the living there is hope" then the next verse says "the living know that they shall die, but the dead know not anything." What this is saying is that there is something that the living can look ahead to---their death, whereas those who are already dead cannot look forward to any comparable death, since their fate is already sealed.
Objection 5) Mary would have to be omniscient and omnipresent to hear all those prayers at once!
Answer: No, omniscience is knowing all things, and omnipresent is being at all places! It might be possible that it be God's will for the righteous in heaven to know all things, or at least to the extent God wills it, 1 Corinthians 13 seems to imply something along the lines of man knowing all things. However, omniscience is not necessary nonetheless, its just knowledge of that petitions addressed to the particular saint that have to be known. Why should we assume God will not give this ability to the saints in heaven? He allowed man on earth to know the thoughts of others as in the case of Elisha, he know the thoughts and plans of the king of Aram (2 Kings 6:12), so its not something God is opposed to giving man the ability to do. There is no need for omnipresence at all, since Elisha did not have to travel any distance to get this information.
Objection 6) It is forbidden to beseech the dead!
The commandment refers to seeking the dead, as in receiving counsel from them as in what King Saul did, the ancient Chaldeans would practice several forms of bizarre witchcraft using bones and stuff to try to summon the dead, my Syrian friend even insisted the word Chaldee comes from the word "magic", I have not been able to verify this elsewhere. Catholics ask the saints in heaven to pray for the Lord for them, we do not seek to get advice from them, we are not trying to lure them to use, nor do we ascribe some unique magical powers to them that are somehow independent of God, rather any power they have are directly from God, just as the bones of Elisha were.
Argument for Intercession of the Saints:
1) Christians are the body of Christ-the church
2) The body of Christ is one undivided body--not a mutant severed body.
3) St Paul teaches the body feels pain in the rest of the body and is able to seek help for it
4) God is able to give the saints in heaven any power He wants
5) Christ said the righteous dead are equal to angels
6) Angels can intercede, are cognizant of the doings of man on earth and can even deliver prayers to God
7) The angels in heaven rejoice over the repentance of one sinner
8) St Paul says at present on earth we see things partially, in the future the partial will pass away.
9) Saints in Revelation 6:9 are presented as asking for vengeance for their deaths
10) Christian, even Protestants have been known for addressing, rebuking Satan, a fallen angel (which they do not believe is forbidden to do)
11) IT would appear the Protestant view has the demons being allowed to be addressed but never God's host & saints in heaven