Daily Reading: (Romans 15:12-13) And again, Isaiah says, “The Root of Jesse will spring up, one who will arise to rule over the nations; in him the Gentiles will hope.” 13 May the God of hope fill you with all joy and peace as you trust in him, so that you may overflow with hope by the power of the Holy Spirit.
Way down the list of adjectives people commonly use to describe God is this one: “God of hope” (Romans 15:13). However, this one attribute tells us that God is the great object of our hope; the main thing we hope for is, the vision, love, and enjoyment of Him (Psalms 73:24).
Before Paul would make this profound statement about God in Romans 15:13 that he is the “God of hope”- he first gave the greatest example of God delivering on something His people had hoped for the most, for the longest amount of time. It was through God delivering on a centuries-upon-centuries old promise that the title “God of hope” becomes most appropriate.
Paul quotes the prophecy of Isaiah (11:10) as a reminder of what was most hoped for a Savior/Messiah. God delivered on the promise He made 750 years after He made the announcement. The answer to the promise was better than what the Jews imagined, salvation available to all people who believe.
Where does hope come from? Romans 15:13 tells us the answer: “May the God of peace/(elpis)” Elpis in the Greek means author of hope. So, hope comes from God. He is the author of hope.
“May the God of hope fill you with all joy and peace as you trust in him, so that you may overflow with hope by the power of the Holy Spirit” (Romans 15:13).
The only source of true joy and peace is God Himself. The only way by which God can give any man joy and peace is by giving him Himself (Romans 15:13).
The privileges of true Christians
The method of securing them
God the source.
Faith in Christ the means.
The Holy Ghost the agent.
(J. Lyth, D.D.)
If you want to be hopeful allow the author of hope to (plēroō) fill you to the full, cause to abound, to furnish or supply liberally, to carry into effect. What is it that God will fill you with? Joy and peace which comes by way of trust in Jesus. Trusting in Jesus leads to joy and peace to abound, and it causes us to overflow with hope.
 Exell, Joseph S. Biblical Illustrator, Volume 5