My thesis is that in the Scripture when God “blesses” men they are thereby helped and strengthened and made better off than they were before, but when men “bless” God he is not helped or strengthened or made better off. Rather (with C. A. Keller in THAT, 1:361) man’s blessing God is an “expression of praising thankfulness” (ein lobendes Danksagen). When the OT speaks of blessing God it does not “designate a process that aims at the increase of God’s strength” (THAT, 1:361). It is an “exclamation of gratitude and admiration” (THAT, 1:357).

This is not at all a strange semantic phenomenon. If God is the primal and inexhaustible “blesser,” then he must be above all others in a “blessed” state — the fullness and source of all blessing. If this is so, then a most natural burst of praise would be “You are blessed!” That this recognition and joyful exclamation of God’s blessedness should then be described as “blessing God” is not unusual. Other analogies, though not exact, would be our expressions like: “I magnify the Lord” or “Let us exalt his name.” Both of these expressions properly recognize and give joyful expression to God’s magnificence and his exalted status. They do not mean that we make God larger or higher. So to bless God means to recognize his great richness, strength, and gracious bounty and to express our gratitude and delight in seeing and experiencing it.

Biblical Support

Here are some texts that have led me to these conclusions:

And you shall eat and be full, and you shall bless the Lord your God for the good land he has given you. (Deuteronomy 8:10)

Here bless is virtually identical to thank or gratefully recognize as the giver of blessing.

Enter his gates with thanksgiving,
     and his courts with praise!
     Give thanks to him; bless his name! (Psalm 100:4)

All your works shall give thanks to you, O Lord,
     and all your saints shall bless you! (Psalm 145:10)

Bless the Lord, O my soul,
     and forget not all his benefits. (Psalm 103:2)

Sing to the Lord, bless his name;
     tell of his salvation from day to day.
Declare his glory among the nations,
     his marvelous works among all the peoples! (Psalm 96:2–3)

Here bless probably means joyfully announcing all these good things about God.

Bless the Lord, O my soul!
     O Lord my God, you are very great!
You are clothed with splendor and majesty. (Psalm 104:1)

This psalm begins and ends with “Bless the Lord, O my soul!” This probably means that the psalm is meant as the blessing. Therefore, blessing God means heartily saying things like “God, you are very great!”

Therefore David blessed the Lord in the presence of all the assembly. And David said: “Blessed are you, O Lord, the God of Israel our father, forever and ever.” (1 Chronicles 29:10)

This is a clear example of what one does when one blesses the Lord: he calls him blessed! The same thing is seen in comparing Genesis 24:27 and 24:48.

I will bless the Lord at all times;
     his praise shall continually be in my mouth. (Psalm 34:1)

I will extol you, my God and King,
     and bless your name forever and ever.
Every day I will bless you
     and praise your name forever and ever. . . .
My mouth will speak the praise of the Lord,
     and let all flesh bless his holy name forever and ever. (Psalm 145:1–2, 21)

Praise the Lord!
     Praise, O servants of the Lord,
     praise the name of the Lord!
Blessed be the name of the Lord
     from this time forth and forevermore! (Psalm 113:1–2)