At times to be joyful is sin. At times God wants us to respond with sorrow. Notice Paul's letter to the Corinthians.
2Corinthians 7:8-11But Israel took lightly the chastening of the Lord. Such is the response also of existentialism, which teaches to smile in the face of hopelessness and despair for no other reason than for the fact that you exist. Such a carefree attitude does not evoke repentance. People commit sin and suffer for it, but don't allow their suffering to invoke repentance from sin. Rather they mock God by celebrating their sinfulness such as can been seen in gay pride parades and the like.
For even if I made you sorry with my letter, I do not regret it; though I did regret it. For I perceive that the same epistle made you sorry, though only for a while. Now I rejoice, not that you were made sorry, but that your sorrow led to repentance. For you were made sorry in a godly manner, that you might suffer loss from us in nothing. For godly sorrow produces repentance leading to salvation, not to be regretted; but the sorrow of the world produces death. For observe this very thing, that you sorrowed in a godly manner: What diligence it produced in you, what clearing of yourselves, what indignation, what fear, what vehement desire, what zeal, what vindication! In all things you proved yourselves to be clear in this matter.
While God is longsuffering, there comes a point at which He will take no more. For example it says, "it is impossible for those who were once enlightened, and have tasted the heavenly gift, and have become partakers of the Holy Spirit, and have tasted the good word of God and the powers of the age to come, if they fall away, to renew them again to repentance, since they crucify again for themselves the Son of God, and put Him to an open shame." Heb 6:4-6 The rejection of God's Holy Spirit which leads one to repentance is an eternal and unforgiveable sin. So best to repent while you have an opportunity to do so.