So Great Salvation

How will any escape that neglect so great Salvation? Why does God Himself call His Salvation 'so Great'? What do we learn from God's Word describing His plan for Salvation by His Son the Lamb slain, 'foreordained' 'before the foundation of the world'? Why is Jesus the Christ named the Author of Eternal Salvation? Why did Christ have to learn obedience in order to make His people who were predestined accepted? Whose power does it take to make a vile guilty sinner a saint? How is Salvation an accomplishment? Since we know salvation had to be earned and the price of the 'called out ones' sin had to be paid how does this solidify Justification accomplished in time at Christ's death on the cross and after His Holy life of obedience?