Psalms 100:1 : The lands are required to receive the good tidings from heaven, which implies that they are to cast off and reject their own gods. They are to turn from idols to serve the living and true God, and to wait for His Son from heaven. A joyful noise is to be made, because a glad message has come.
Psalms 100:2 : He who sends the message claims obedience. "Serve Jehovah." There is sorrow not in the service, but for not having served before; and there is sorrow remaining because the service is still so poor and defective. But there is no sorrow in the service.
Psalms 100:3 : That Jehovah may be really served, He must be known. Jehovah is a God of wisdom, and He will have an intelligent worship. To know that Jehovah is God is to know His character and perfections as revealed in Holy Scripture, and most specially as revealed in Christ Jesus, His Son, in whom all lies in perfect harmony and most glorious display.
Psalms 100:4 and Psalms 100:5 : The exercises which we are here called unto are praise, and blessing, and thanksgiving: praise because of God's excellences; blessing because of the happiness of God in Himself; thanksgiving because of His benefits.
J. Duncan, The Pulpit and Communion Table,p. 344.
References: Psalms 100:2. Spurgeon, Evening by Evening,p. 9; Ibid., Sermons,vol. xiii., No. 769. Psalms 100:3-5. Ibid.,vol. xx., No. 1197. Psalms 100:4. Ibid., Evening by Evening,p. 312.Psalms 100:5. Ibid., Sermons,vol. xxi., No. 1265.