Hebrews 7 25: "wherefore he is able also to save them to the uttermost that come unto God by him seeing he ever liveth to make intercession for them"
This passage shows that Jesus is our intercessor, not Mary or any of the other saints.
Hebrews 8 1: "now of the things which we have spoken the sum we have such an high priest who is set on the right hand of the throne of the majesty in the heavens"
2000 years ago when this was written, Christ was already in the Holy of Holies, seated on the right hand of the Father. He didn't enter into the Holy of Holies in 1844 as the Seventh Day Adventists say.
Hebrews 9 27: This verse clearly disproves reincarnation.
Hebrews 10 26: This verse is clear on the subject of whether or not you can loose your salvation.