The Old Testament is a Christian book. Jews claim it as their own, and Muslims make reference to it. But for the church the Old Testament is a Christian book. It constitutes God's Promise to redeem the world in the fullness of time in Christ. (Gal. 4:4). In this respect the New Testament could be considered the last chapter of the Old Testament, for it comprises the fulfillment of the promise via the death and resurrection of Christ.

The New Testament is not merely a record of the fulfillment, but the inscripturated Word given voice, and sacramentally enacted among the baptized, is the fulfillment itself. 

This being the case we should read the Old Testament in light of the New. Psalm 111 (Epiphany 4 - Series B) is an example.

1 Praise the LORD! I will give thanks to the LORD with my whole heart, in the company of the upright, in the congregation.

Commentary: This verse is a prediction of the assembly (company) of the baptized (upright) in Eucharistic worship (give thanks). It bespeaks faith (whole heart) that is born in us by the "word of truth." (James 1:18)

2 Great are the works of the LORD, studied by all who delight in them. 3 Full of splendor and majesty is his work, and his righteousness endures forever.

Commentary: The death and resurrection of Christ are the "great works of the Lord" that are "studied" by all in the Great Congregation (Psalm 22). The cross is "full of splendor and majesty" and the salvation gained thereon is "righteousness that endures forever."

4 He has caused his wondrous works to be remembered; the LORD is gracious and merciful. 5 He provides food for those who fear him; he remembers his covenant forever. 

Commentary: Here again is a prophecy of the Christian church celebrating the Eucharist, which is the fulfillment of every Old Testament ceremony ever enacted, or sacrifice made. But the Eucharist is not merely psychological recall as Protestants interpret the word "remembrance". But it is a factual participation in, and a receiving of all the benefits of, the Lord's one, great, all-sufficient sacrifice made to bring salvation to the world. ("This is my body given for you for the remission of sins.")

6 He has shown his people the power of his works, in giving them the inheritance of the nations. 7 The works of his hands are faithful and just; all his precepts are trustworthy; 8 they are established forever and ever, to be performed with faithfulness and uprightness. 9 He sent redemption to his people; he has commanded his covenant forever. Holy and awesome is his name!

Commentary: Though the fulfillment of the Promise took thousands of years we are consoled all the more because God never forgets. He lines up all things in heaven and earth, and at the "right time" (Romans 5:8) he performs his Promises for us flawlessly. Hope, keeps us alive. It is our food and fuel. But we receive more besides. All along the way, as God is busy "working out all things for our good" (Romans 8:28) he fills our lives with blessings and gifts to strengthen, comfort, console and enliven us. He gives us family, friends, food, clothing, peace of mind, mysteries to occupy our minds, relief from the troubles of life (which all have an expiration date - because the only thing that "endures forever" is he mercy). And so "be still" says the Lord to the storms of your life. God's perfect care for you does not only extend over "life's little day," but eternally. The Psalm then concludes with this summary versicle and response: 

V: The fear of the LORD is the beginning of wisdom;
R: all those who practice it have a good understanding.
All: His praise endures forever!