Albert Barnes' Bible Commentary
Job 21:15
What is the Almighty, that we should serve him? - compare for similar expressions, Exodus 5:2; Proverbs 30:9. The meaning here is, “What claim has the Almighty, or who is he, that we should be bound to obey and worship him? What authority has he over us? Why should we yield our will to his, and why submit to his claims?” This is the language of the human heart everywhere. Man seeks to deny the authority of God over him, and to feel that he has no claim to his service. He desires to be independent. He would cast off the claims of God. Forgetful that he made, and that he sustains him; regardless of his infinite perfections and of the fact that he is dependent on him every moment, he asks with contempt, what right God has to set up a dominion over him. Such is man - a creature of a day - dependent for every breath he draws on that Great Being, whose government and authority he so contemptuously disowns and rejects!
And what profit should we have, if we pray unto him? - What advantage would it be to us should we worship him? Men still ask this question, or, if not openly asked, they “feel” the force of it in their hearts. Learn hence,
(1) That wicked people are influenced by a regard to “self” in the inquiry about God, and in meeting his claims. They do not ask what is “right,” but what “advantage” will accrue to them.
(2) If they see no immediate benefit arising from worshipping God, they will not do it. Multitudes abstain from prayer, and from the house of God, because they cannot see how their self-interest would be promoted by it.
(3) Men “ought” to serve God, without respect to the immediate, selfish, and personal good that may follow to themselves. It is a good in itself to worship God. It is what is “right;” what the conscience says “ought” to be done yet
(4) It is not difficult to answer the question which the sinner puts. There is an advantage in calling upon God. There is
(a) the possibility of obtaining the pardon of sin by prayer - an immense and unspeakable “profit” to a dying and guilty man;
(b) a peace which this world cannot furnish - worth more than all that it costs to obtain it;
(c) support in trial in answer to prayer - in a world of suffering of more value than silver and gold;
(d) the salvation of friends in answer to prayer - an object that should be one of intense interest to those who love their friends:
(e) eternal life - the “profit” of which who can estimate? What are the few sacrifices which religion requires, compared with the infinite and immortal blessings which may be obtained by “asking” for them? ‘Profit! ‘ What can be done by man that will be turned to so good an account as to pray? Where can man make so good an investment of time and strength as by calling on God to save his soul, and to bless his friends and the world?