Mediator of what? Clearly Scripture shows the Blessed Virgin Mary was an intercessor superior to even Abraham.
And the Scripture telling us this would be where?
"For there is one God, and one mediator between God and men, the man Christ Jesus" -- 1 Timothy 2:5
Giving the mother of Jesus the title of "co-redeemer" and "dispensatrix of all grace" is vile idolatry which contradicts God's word, and denies the atonement.
If any man have an ear, let him hear. He that leadeth into captivity shall go into captivity..." -- Rev. 13:6,9-10"And he opened his mouth in blasphemy against God, to blaspheme his name, and his tabernacle, and them that dwell in heaven...