What is christianity about?

"But I with the voice of thanksgiving will sacrifice to you; what I have vowed I will pay. Salvation belongs to the LORD!” These words from the prophet Jonah (2:9) are an accurate description of Christianity. The Bible, from beginning to end, is one story -- Salvation belongs to the LORD! To quote Tim Keller: "In ourselves we are infinitely more sinful than we can possibly imagine but, in Christ we are infinitely more loved than we could ever hope for." 

How can this be? 

TIM KELLER - How does someone get to heaven? (1)

TIM KELLER - What is the Gospel? (1)

MICHAEL HORTON - The Doctrine of Justification (2)

R.C. SPROUL - The importance of Justification (1)

"Oh, the depth of the riches and wisdom and knowledge of God! How unsearchable are his judgments and how inscrutable his ways!" Romans 11:33