The Spirit of Christ Within

Why does God's Word never say anything good about men? How does the Word teach us that it is ONLY God that is good? How do we see that David was the writer physically but the Holy Spirit of Christ was the Author? How do we see the Gospel is through out the entire Word of God in the Old Testament and the New? How does reproof, correction and instruction in Righteousness pertain to Christ alone? Why did Christ need the Holy Spirit? Why is Christ the Last Adam? Why did Christ need a body? Why did Christ have to learn obedience as a man in time?