It is a central principle of Christianity that humans naturally seek to be happy. Now this desire for happiness often goes askew – and this is sin. Sin a sort of failure to actually achieve happiness. As it reads in Proverbs 13:15, “the way of transgressors is hard.”

This is not say that happiness is the immediate lot of the Christian. As Jesus himself says, “In the world you will have tribulation.” John 16:33. Rather this happiness is not found in the world; it is a gift of God.

Thomas Watson commenting upon the text

So let no one boast in men. For all things are yours whether Paul or Apollos or Cephas or the world or life or death or the present or the future-all are yours and you are Christ’s, and Christ is God’s. 1Cor3.21-23. Writes as follows

Happiness is the mark and centre which every man aims at. The next thing that is sought after Being, is being happy; and surely, the nearer the soul comes to God, who is the fountain of life and peace, the nearer it approacheth to happiness; and who so near to God as the believer, who is mystically one with him? he must needs be the happy man: and if you would survey his blessed estate, cast your eyes upon this text, which points to it, as the finger to the dial: ‘For all things are yours

And so the happiness is to be found in God. Augustine begins from a different place. In the City Of God, he casts his eye upon the pagan gods of the Romans. Happiness is what we should seek, but who could find happiness among such gods?

For, to whom—if not to Felicity alone—should men who want eternal life dedicate themselves, if, indeed, Felicity were divine. But, since happiness is not a goddess, but a gift of God, to what God save the Giver of happiness should we consecrate ourselves? For, we love with religious charity that eternal life where there is a true and complete beatitude. I think, from what I have said so far, that no one can imagine that the Giver of happiness is any of those gods who are worshiped with such indecent rites, and are more indecently angry when they are not so worshiped, and who thus show themselves to be nothing but unclean spirits.