He is nevertheless our sole mediator, redeemer, defender that sits at the right hand of God the Father (1 Peter 2; Rom. 8). The saints are not mediators, intercessors, nor is the virgin Mary a mediatrix
Related quotations
As Christ alone is our mediator and redeemer, none of the saints nor even the most blessed virgin Mary (even though we recognize her as the most blessed among women and praiseworthy above all others as the mother of God) may be called mediators between God and men. Nor is it to be assigned to Mary to be the queen of heaven with lordship over all creatures, which is the province of Christ alone.
It may be added also that the doctrine of the Papists that the saints or the Virgin Mary may act as mediators to procure blessings for us, is false. There is but "one Mediator;" and but one is necessary. Prayer offered to the "saints," or to the "Virgin," is idolatry, and at the same time removes the one great Mediator from the office which he alone holds, of making intercession with God.
However, we cannot in any way acknowledge or accept what our opponents openly say, namely that Mary is to be invoked as a mediator between God and humans, or that she is our patron and advocate. We do not believe that this is either a tradition of Holy Scripture or a command from God. We believe that God, who alone grants all salvation for the present and future, is the one to be invoked alone. We believe that Christ alone [since He alone is true God and true man] is the true mediator between God and humans. We believe that He, who alone can satisfy all humans, is the patron and advocate with the Father.
But can she not furthermore be venerated as a mediator and intercessor between God and us with the honour of invocation? Answer: No, since no one should be invoked except God alone in Christ, our only Mediator, Saviour, and Intercessor