Yahweh the Revealer
Psalm 19 is a "Thanksgiving Psalm" written by David; the occasion of his writing this Psalm is unclear. In this Psalm, David is praising the God who reveals Himself in a general way through nature and in specific ways through His Word. In response to God's revelation, David is aware of his propensity to sin and his need for inner purity.
This Psalm contains four distinct units:
1) God (Elohim) is Creator, revealing Himself through nature (1-6)
2) God (Yahweh) is Lawgiver, revealing Himself through the Word (7-11)
3) David's need for preservation against sin (12-13)
4) David's need to be an acceptable sacrifice (14)
Observation: The heavens are like a choir singing two parts—one at night, one in the morning—both led by Elohim, and the voice of these heavenly singers is heard universally. The word of Yahweh is even more spectacular for it is perfect, having a special ability to revive the soul at levels that Creation's revelation of God never can. The law is a treasure to be both coveted and savored (Elohim, God's creative name; Yahweh, God's redemptive name).
Purpose: Revealing how to pray as God reveals Himself to our heart in nature or His word, and then how to respond to God as He reveals Himself, being aware of our propensity to sin and our need for inner purity.
Yahweh the Savior
Psalm 20 is a "Royal Psalm," a prayer of trust before a battle, revealing Yahweh as King of the battle to come. It is believed this Psalm was written during the period of David's battles as recorded in 2 Samuel 8, or maybe even his battle with the Ammonites leading up to the sin with Bathsheba.
The Psalm consists of two verses with a concluding chorus of praise:
1) A prayer of intercession by the congregation for victory (1-5)
2) A prayer of confidence by the king for victory (6-8)
3) A prayer of thanksgiving by the congregation for victory (9)
Purpose: Revealing how to pray before facing some opposing force or circumstance purposed to defeat you.
Yahweh the Savior
Psalm 21 is also a "Royal Psalm." Psalm 20 is a Psalm prepared to be sung during the sacrifice, as an intercession for an upcoming battle. Psalm 21 was written as a Psalm of thanks for victories already granted in battle.
Like Psalm 20, this Psalm consists of two verses with a concluding chorus of praise:
1) Thanksgiving for past victory (1-7)
2) Expectation for future victory (8-12)
3) Praise for Yahweh's strength in victory (13)
Purpose: To show us how to pray when God has given us victory so we will remind ourselves that past victory comes from the Lord, as will future victories.