Now, I do think Christians should be encouraging people, and I do think following Jesus is a path to joy and peace, and I do think God is great. But my life is not always positive. Singing songs that say it is does not encourage me. And there are times when following Jesus is a long, hard, lonely path that does not yield much in the way of immediate happiness or satisfying answers.
I recently had a conversation with someone who thought it was a good idea to use many of the same songs from K-Love's playlist in worship (and many of those songs, at first blush, seem to fit that purpose) because new Christians could listen to the songs on the radio all week, allowing them not only to learn them but also to start practicing worship as a lifestyle, rather than an event just on Sunday morning. In theory, this seems like a good idea.
The problem is that the path of following Jesus is not positive and encouraging, not most of the time. The people Jesus calls "blessed" do not have much to be positive or encouraged about. They are poor, hungry, empty of power, persecuted, to name a few. Even the pure in heart have to live among the rest of us, whose hearts are full of ugliness and pain and selfishness. Jesus is friend of sinners, but also speaks "Woe!" seven times in Matthew chapter 23. And of course, he suffered humiliation, betrayal, and death--John reminds us at the outset that "his own did not receive him."
I've read many places that at least one third of the Psalms are laments. The book of worship from the pinnacle of the ancient Israel's worship is filled with songs of desperation, sadness, anger, and questioning.
Worship does not pretend. God, who sees all, does not need us to put on our happy face. He does not want us to, because that is lying to him, hiding from him. It is the first consequence of sin, that we run away from God and try to hide our nakedness. The reason Christians are free to worship honestly is because God's approval of us is not dependent on us. We cannot become presentable to God. We do not have to be.
These are not new ideas. From the beginning, the mark of Christians has been sharing everything with one another, confessing and praying with one another, and recognizing, through wine and bread, that our righteousness before God is not of our own making.
There is nothing that can separate us from God's love. Not negativity or discouragement or anger, or any of the other things that are inevitable in a world that fall short of the glory of heaven--and we shouldn't hide these things from God, either. That is the kind of worship I hunger for.