Here are my answers, from my book (see my signature).
What are we thanking God for when we say “Thanks be to God”? Two Scripture passages, Romans 7 and 2 Corinthians 9, give us some insight.
In Romans 7, St. Paul writes about the internal struggle we all face, even after Baptism: we do the evil which we do not want to do, and we do not do the good which we want to do:
[INDENT]I do not understand my own actions. For I do not do what I want, but I do the very thing I hate. … I can will what is right, but I cannot do it. For I do not do the good I want, but the evil I do not want is what I do. … So I find it to be a law that when I want to do right, evil lies close at hand. For I delight in the law of God, in my inmost self, but I see in my members another law at war with the law of my mind and making me captive to the law of sin which dwells in my members. Wretched man that I am! Who will deliver me from this body of death? Thanks be to God through Jesus Christ our Lord! So then, I of myself serve the law of God with my mind, but with my flesh I serve the law of sin. (Rom. 7:15-25)
This conflict between his “inmost self” (his soul which has received an indelible mark in Baptism) and his “members” (his flesh which is still under the power of his earthly desires) is common to all of us: the term the Church uses for it is concupiscence, the tendency of human nature to sin as a result of our inability to subordinate our desires to the dictates of reason. Faced with his own wretchedness, St. Paul thanks God for His Son Jesus Christ Who delivers him from his “body of death.”
In 2 Corinthians 9, St. Paul is writing about the generosity of the people of Corinth. The Corinthians were such zealous and ready givers that he had bragged about them to others in Macedonia. He tells them that their generosity is only possible because of God’s generosity: “God is able to provide you with every blessing in abundance, so that you may always have enough of everything and may provide in abundance for every good work.” (2 Cor. 9:8) He concludes:
You will be enriched in every way for great generosity, which through us will produce thanksgiving to God; for the rendering of this service not only supplies the wants of the saints but also overflows in many thanksgivings to God. Under the test of this service, you will glorify God by your obedience in acknowledging the gospel of Christ, and by the generosity of your contribution for them and for all others; while they long for you and pray for you, because of the surpassing grace of God in you. Thanks be to God for his inexpressible gift! (2 Cor. 9:11-15)
Three times he speaks of thanks to God: thanksgiving for His great generosity of grace, the “inexpressible gift” of God.
It is for these two things that we say “Thanks be to God” at the end of the readings from Scripture. First and foremost, we recognize that in the Scriptures being proclaimed, we are hearing God’s word which the Holy Spirit inspired various men to put into writing. In Scripture, the phrase “the word of the Lord” means, quite simply, a revelation directly from God. In Jesus, this Word of God is enfleshed: Christ is the Word-made-Flesh. As Vatican II said in the Dogmatic Constitution on Divine Revelation, Dei Verbum (DV), Jesus Christ “is both the mediator and the fullness of all revelation.” (DV 2)
Secondly, we acknowledge the pure love that God shows for us in bestowing His “surpassing grace” upon us, that we may hear His word proclaimed to our ears. Jesus said “blessed are your eyes, for they see, and your ears, for they hear” (Matt. 13:16), and again, “Blessed rather are those who hear the word of God and keep it!” (Luke 11:28) St. John begins his book of Revelation with these words: “Blessed is he who reads aloud the words of the prophecy, and blessed are those who hear, and who keep what is written therein.” (Rev. 1:3) There are many eyes and ears in the world that go without reading or hearing the Sacred Scriptures; as we thank God for His grace, we must not forget the mission of the Church to spread the Gospel throughout all the world.
[RIGHT]Praying the Mass: The Prayers of the People, pp. 59-61[/INDENT]