Psalm 100 (CSB) — 1 Let the whole earth shout triumphantly to the LORD! 2 Serve the LORD with gladness; come before him with joyful songs. 3 Acknowledge that the LORD is God. He made us, and we are his — his people, the sheep of his pasture. 4 Enter his gates with thanksgiving and his courts with praise. Give thanks to him and bless his name. 5 For the LORD is good, and his faithful love endures forever; his faithfulness, through all generations.
Theodoret of Cyr (c. 393-466) comments on this Psalm:
“Serve the Lord with gladness,” for the kingship of our God and Savior has nothing of the harsh tyranny of the devil; rather, his lordship is mild and loving.
COMMENTARY ON THE PSALMS 100.1.1
Cassiodorus (c. 485–c. 580) likewise comments:
“Serve the Lord in gladness; enter his sight with rejoicing.” But that joy is love, at any rate, which (as the apostle says) “is not puffed up, does no harm, is not ambitious” and all the other things which describe this excellent virtue… Therefore, they are those who serve the Lord in gladness, who love him above all things and regard one another with brotherly love…
EXPOSITIONS OF THE PSALMS 99.2.7
Now behold the faithful love of God that endures forever through all generations:
1 Peter 2:21–25 (CSB) — 21 For you were called to this, because Christ also suffered for you, leaving you an example, that you should follow in his steps. 22 He did not commit sin, and no deceit was found in his mouth; 23 when he was insulted, he did not insult in return; when he suffered, he did not threaten but entrusted himself to the one who judges justly. 24 He himself bore our sins in his body on the tree; so that, having died to sins, we might live for righteousness. By his wounds you have been healed. 25 For you were like sheep going astray, but you have now returned to the Shepherd and Overseer of your souls.
It is in this love, like someone who finds a cool spring to drink from, that our souls are renewed and we find life forevermore.
Biblical Reasons 