Today is Thanksgiving Day, a day where we are officially (in the words of institution by President Lincoln in 1863) to "set apart and observe the last Thursday of November . . . as a day of Thanksgiving and Praise to our beneficent Father who dwelleth in the heavens" for all his gifts in life. Lincoln rightly recognized that we are to be thankful to God for his grace--his unmerited kindness and favor toward us as sinners: "While dealing with us in anger for our sins, [God] hath nevertheless remembered mercy" (likely an allusion to Habbakuk 3:2).
Without grace, there is no thanksgiving. If our world were governed by an entirely quid pro quo system, tit-for-tat, where all was earned as payment for duty or obligation, we would have no reason to say "thank you" to anyone. All would be our just deserts. It is only when someone does something good for us that we really don't deserve, that we can say "thank you." (See Romans 4.)
At its very core, gratitude is rooted in grace. Our English "gratitude" and the Italian grazi ("thank you") come from the Latin gratias ("grace"). God has been good to preserve a fundamental, if flawed and feeble, recognition of this throughout the world. No matter where you may travel, sinful people are still bearing the image of their Creator, doing good to others and (sometimes) receiving replies of "thank you."
Paul's letter to the Colossian church demonstrates that among the chief Christian virtues is thankfulness. "We always thank God . . . when we pray for you" (1:3). "May you be strengthened with all power . . . , giving thanks to the Father" (1:12). We are to live our lives rooted in Christ Jesus, "abounding in thanksgiving" (2:7). "As the Lord has forgiven you, so you also must forgive. . . . And let the peace of Christ rule in your hearts, to which indeed you were called in one body. And be thankful. Let the word of Christ dwell in you richly, . . . with thankfulness in your hearts to God. And whatever you do, in word or deed, do everything in the name of the Lord Jesus, giving thanks to God the Father through him" (3:13, 15-17).
We are to live "with thankfulness [charis] in our hearts to God." Charis is the Greek word used throughout the New Testament to refer to grace, God's love for sinners on account of Christ. We live with grace in our hearts. And the outflow of this is gratitude. Even the adjective "thankful" in verse 15 is eucharistos. We can be thankful only because we recognize God's grace and favor.
Without the compassionate, forgiving love of God rooted in his Son and poured out through his Spirit (Romans 5:5), we would live in a cold world of duty and wages. And if this were God's core modus operandi, our chief attitude should be one of fear, "for all have sinned," and "the wages of sin is death" (Romans 3:23; 6:23). But we rather live in a world of a giving and forgiving God. "For the wages of sin is death, but the free gift of God is eternal life in Christ Jesus our Lord" (6:23).
So don't forget that the food on your table today and the family or friends you're with are gifts. You didn't deserve them, you didn't earn them. The day off of work is a gift--and you should celebrate it with enjoyment and rest. And above all, today should be for looking to Jesus Christ on the cross, the very demonstration of God's goodness and grace toward us in this life and the next.