Founder of Our Salvation

"Jesus took upon himself our humanity. He was fully God and fully human. And just like we die, he died. But through his death he destroyed death. "Since therefore the children share in flesh and blood, he himself likewise partook of the same things, that through death he might destroy the one who has the power of death, ... Therefore he had to be made like his brothers ..., so that he might become ... high priest in the service of God, to make propitiation for the sins of the people. ..." Hebrews 2:14-18 * Who made Martin Luther such an authority that he could remove several books of the Bible? * Would you please explain the difference between "sinner" and "sinful nature"? * How are we to give as New Covenant believers? * Why do so many reject the New Covenant?