This question unfortunately has different layers.

1 Timothy 2:5 does indeed proclaim the fact that Jesus is the one Mediator between God and man, and this is certainly true, since he is the only God-man and thus the only possible Mediator in that sense. However, this does not exclude the idea of other people praying for us, whether in heaven or on earth.

Evidently the verse emphasizes that salvation is only thrugh Jesus.This mediatorship is a priestly mediatorship typifid by the Aronic priest who took the blood of sacfrifice and entered into the holy of holies as an atonement for sins. It is the blood of Jesus that covers sins and brings salvation. The prayers of the saints (which in Bible simply consists of all believers who are redeemed by the blood - called by Peter as the Royal Priests) are exhorted everywhere in the scripture. In fact James proclaims that the prayer of the righteous availeth much. In this sense any christian is a mediatrix.

The real question therefore lies not in whether a christian can be a mediator or not, but whether Mary can be a mediator now in the sense every christian is a mediator. There is no difficulty in our understanding Mary praying with the rest of the christian community which she evidently did in her life time. The problem raised by the Mediatrix proposition is not whether Christian believers should pray or not.

It is closely intertwined with the problem of concept of sainthood and the intercession of the dead. Is there a special class of people called saints? Who are these saints? Evangelicals consider all believers as saints. Early apostolic epistles were addressed to the saints in a given area. The scripture do not know any other form of saint. All christians are justified and are in the process of sanctification to perfectness and none are perfect. In fact before the law all men stand condemned however righteous they are. Our righteousness are like filthy rags.

The second aspect in question is what is the status of these saints after their death. Even though evangelicals do not believe in any intermediary state of purgatory where varying degrees of punishment are given to the saints to make them pay for their sins (as though the sacrifice of Jesus was insufficient for this purpose) evangelicals also believe that the spirits of the saved (i.e. those who had put their faith in Jesus) are in the presence of God. There are others who believe that all dead are asleep and will be woken up at the last trumpet. So there is no question that the dead believers are alive in the sense that spirits are alive. Assuming also that Mary is alive and is assumed and live with a body we still have problems of extension. Are they localised beings or are they omnipresent and omniscient. If the dead are not omnipresent how are they to hear your prayers? If they are not omniscient how are they to hear the prayers rendered with your mind?

I do ask my christian brothers to pray for me. I have to go to the place where they are and vocally communicate my need to them. How am I to do that with a localised spirit. How can I communicate with the spirits? Evidently we are dabling in spiritism and seance etc which are clearly forbidden by the law. Was it ever revoked in the New Testament? Are the spirit of the saints roaming around us? African pagan religion is based on that. Are we to justify that. In fact the pagan religion is based on just that world view. The spirit of the dead never leave this world. They are around the place where they lived and are as much involved in the life as they were living. In most African homes they build a seperate home for these dead ancestors and always consults them and keep them humored. In fact they do consider the ancestors as mediators between them and God. This they can do because they are spirits without a body and so can move around freely. They are still limited by space and time. So in order to allow for intercessory powers to the dead saints we need to ascribe many properties that are particualrly the properties of God himself.

Assuming that the dead are still alive and they are interested and are involved in the life of friends and relations and that they can hear the prayers (they are omnipresent or they hear sometimes and they read our minds by telepathy), intercession of the dead saints are acceptable. These I do not want to discuss.

But that does not give Mary any particular status as Mediatrix. For this we need another thread of logic. Mary is a saint ( In Catholic thinking this is something a person earned by right by their own effort. It does not involve any grace). Though she died, she was asumed body and soul into the heavens because she was sinless in birth - without original sin and without personal sin. So Mary is like Jesus himself in her status before God. Having assumed she sits besides God himself. (for whom she was the wife in flesh to bring God Jesus to birth) Being the Mother she can command Jesus. The Son cannot disobey Mother. Can he?

But is that all? Far from it. Catholic cult now produces a place for Mary equal to the trinity and goes one step further to state that salvation can only be obtained through Mary. Read this quote:

So Pope Leo has put another ladder in the emanation of God which the gnostics assumed in Mary.

God =====Jesus Christ =======Mother Mary ======>"O Virgin most holy, none abounds in the knowledge of God except through thee; none, O Mother of God, attains salvation except through thee; none receives a gift from the throne of mercy except through thee."

There is no salvation except through Mary! An explicit statement of this can be found in the Encyclical titled Iucunda Semper Expectatione by Pope Leo XIII Sept 8., 1894

" We must never go to Our Lord except through Mary, through her intercession and her influence with Him. We must never be without Mary when we pray to Jesus.......Beware, predestinate soul, of believing that it is more perfect to go straight to Jesus, straight to God. Without Mary, your action and your intention will be of little value; but if you go to God through Mary, your work will be Mary's work, and consequently it will be sublime and most worthy of God."( The Secret of Mary, St. Louis Marie de Montfort, Montfort Publications, Bay Shore, New York 11706, Imprimi potest, Nihil obstat and Imprimatur of the Catholic Church)

This statement has more serious theological implications than that meets the eye.

Rom. 3:21 But now a righteousness from God, apart from law, has been made known, to which the Law and the Prophets testify.
22 This righteousness from God comes through faith in Jesus Christ to all who believe. There is no difference,
23 for all have sinned and fall short of the glory of God,
24 and are justified freely by his grace through the redemption that came by Christ Jesus.

Rom 5:17 For if, by the trespass of the one man, death reigned through that one man, how much more will those who receive God's abundant provision of grace and of the gift of righteousness reign in life through the one man, Jesus Christ.
18 Consequently, just as the result of one trespass was condemnation for all men, so also the result of one act of righteousness was justification that brings life for all men.
19 For just as through the disobedience of the one man the many were made sinners, so also through the obedience of the one man the many will be made righteous.

The righteousness that brings justification is not the righteousness of Mary, but that of Jesus which comes not by faith in Jesus Christ and that alone.If a Christian can receive imputed righteousness of Mary, then we can simply short circuit Jesus. Notice Pope does that in the following statement:"but if you go to God through Mary, your work will be Mary's work, and consequently it will be sublime and most worthy of God" Jesus is no consequence to us.Then the real sequence will be:

The door through Jesus got stuck because you do not have enough righteousness!!

This is the real meaning of Mary Mediatrix. It is this that Catholic apolegeticians try to play down in their replies all the time. Pope Pius X (Feb 2, 1904 in Encyclical Ad Diem Illum Laetissimum) goes on to ridicule those who find this new intermediary unnecessary and unscriptural thus::

"... Those, alas! furnish us by their conduct with a peremptory proof of it, who seduced by the wiles of the demon or deceived by false doctrines think they can do without the help of the Virgin. Hapless are they who neglect Mary under pretext of the honor to be paid to Jesus Christ! ..."

"Just as there is no salvation outside of belonging to the Catholic Church, which is the immaculate Bride of Christ, there is no communication of divine grace without the intercession of the Virgin Mary, who acts as the channel of God's gifts". (Peter A. Kwasniewski Catholic Information Center on Internet. )

So the real series involves another mediator.

Only we may short circuit Jesus if you have devotion to Mary.

Does this violate the scripture:

Such a Mary Mediatrix was not even in the dreams of the Christian Church in the Apostolic Age.