This entire psalm is a great song of praise and worship that declares the goodness and mercy of God to all people. He is faithful and true, and His grace extends to each nation of the world and every tribe of Israel – forever and ever.
Although this psalm begins with an explosion of praise and a great celebration of the might, majesty, dominion, and power of our Sovereign God and Eternal Creator, the final verse points us to the goodness and grace of our Lord and Saviour Whose mercy is everlasting and Whose truth endures through time and into eternity – for He is the Way and He is the Truth. He is the only One in Whom are the words of eternal Life – for all who believe in Him.
The Lord is without question good, and His mercy and grace most certainly endure through all generations, because He purposed before the foundation of the world to redeem the lost race of fallen mankind through the sacrificial offering of His only begotten Son. God in His grace purposed to reinstate man's rule over His creation, through the Person and Work of His only begotten Son.
It is for all these reasons, that the Gentile nations and Israel are jointly called upon to enter into His gates with thanksgiving in their heart, to come into His courts with praise, and to give thanks to Him and bless His name forever. Both Jew and Gentile alike are summoned to believe on the Lord Jesus Christ, Who has paid the price for our sin and has in Himself, the Word of eternal life.
In the time of David when this song of thanksgiving was written, it was worshippers of Israel who would process through the gates of the city of Jerusalem and up to the Temple of the Lord, with songs of praise on their lips. But the veil of the Temple has been torn in two, from top to bottom, inviting whosoever will to come and worship at the feet of our God and Saviour.
Jew and Gentile, old and young, male and female, bond and free, are all exhorted to: "Enter His gates with thanksgiving and into His courts with praise." Everyone is summoned to: "Give thanks to the Lord, for He is good and to bless His holy name forever, for Christ died to pay the price of our sins and is risen to give us life immortal."
Let us all shout joyfully to the Lord and serve Him with gladness. Let us come before Him with joyful singing and know that the Lord Himself is God Almighty Who has made us, and not we ourselves. Praise God that by grace through faith we are His people and the sheep of His pasture.
Let us enter into His gates with thanksgiving and His courts with praise, and let us give thanks to Him and bless His name, for the Lord is good, His lovingkindness is everlasting, and His faithfulness endures throughout all generations.
Source: https://dailyverse.knowing-jesus.com/psalm-100-4
