The theme of this text, and the core of last week's teaching, is God's rebuke to religious people who try to live in two worlds at the same time. Specifically, it's a rebuke to people who try to "keep up" the forms of their religion while they "choose their own ways"(4) in the parts of their lives not lived in the Temple.
The way they convince themselves that this charade will last is by telling themselves the Temple is God's House. It's where God does His "God stuff." And then it's easier to tell themselves that when they're not in the Temple - or on their way to or from church, or youth night, or prayer meeting, or Praise Band practice - then they are "on their own time," so to speak. But God says this isn't so. He isn't contained in any man-made structure or religious system. He is the Creator of each one of us and claims sovereign interest over all our thoughts, moments and choices.
So the key point of last week's teaching was these weren't "bad to the bone" people. Their sin was they were partial in the recognition of God's claim on their time. Certainly God had the right to prescribe sacrifices, and fasts and ceremonies - all the religious stuff - all the temple stuff. Choirs, offerings, Bibles, communion - that sort of stuff was God's turf. But they reserved the right to pursue their own agendas and desires when they were away from the temple. In the words of our text, they "chose their own ways."