Thanksgiving is the act of showing gratitude to God for all his good deeds. Christians must offer thanksgiving to God because he dwells in it.
The Bible reference
“Enter into his gates with thanksgiving, and into his courts with praise: be thankful unto him, and bless his name. For the LORD is good; his mercy is everlasting; and his truth endureth to all generations”.
(Psalm 100:4-5 NIV)