Why do Catholics recite the phrase "Thanks be to God" during Mass?
They say this many times too. After the priest speaks, the congregation follows in unison, "Thanks be to God."
It is the English translation of Deo Gratias, which is repeated “in thanksgiving for the graces received at Mass” (Catholic Encyclopedia).
"Thanks be to God" is the congregational response given after a reading from the Bible in the Catholic mass. Christians give thanks to God for revealing Himself to us through His Word.