I heard recently that a person approached the pastor of a church and said, "We are leaving the church. We are just not happy here." This struck me as rather odd. Perhaps there were extenuating factors--not feeling welcome, not fully involved, etc. --but the idea that "happiness" should be the criteria for church involvement is rather bizarre. In the verse above, it is clear that Jesus' teaching did not make some people happy.
Don't get me wrong. Everyone wants to be part of a congregation where she or he is accepted, loved, and engaged. This does not necessarily mean that one leaves every Sunday feeling "happy."
One might leave feeling challenged. As a result of approaching the Holy God in worship, one might come away with a desire to walk closer to God.
One might leave with a different set of priorities. As a result of hearing the Word of God, a person might be convicted that service and care for others are more important than some of the other things he or she has been doing.
One might leave with a deeper commitment to grow as a believer. Through times of praise and reflection, a person might desire to practice disciplines of prayer, Bible study, and service that will build one's faith.
And perhaps one might leave happy to know that God has forgiven his or her sins by grace through faith--but I don't that is what the unhappy person above was seeking.
But to leave happy? If anything, the best that anyone can receive from the gathering of the faithful and take into one's daily life is an awareness of the need to be God's person in the world, a sinner saved by grace who has spent a time in fellowship with other sinners worshipping God. It seems to me that is our purpose and it may just make God happy.