From Tullian Tchividjian:
So, here’s a good litmus test: whether it’s a sermon, a book, a blog post, or a tweet–if the lasting impression you get causes you to focus more on what you must do than on what Christ has done, the gospel has not been communicated and the communicator (albeit, unwittingly) is no better than the Pharisees who were charged by Jesus with “tying up heavy burdens, hard to bear, and laying them on people’s shoulders” (Matthew 23:4). Beware of preaching that, in the words of Herman Bavinck, “acknowledges that we are justified by the righteousness of Christ but then seems to think that we are then sanctified by a holiness we ourselves have acquired.” It is through the preaching of the gospel that Jesus summons sinners (both Christians and non-Christians) and says, “Come to me, all who labor and are heavy laden, and I will give you rest. Take my yoke upon you, and learn from me, for I am gentle and lowly in heart, and you will find rest for your souls” (Matthew 11:28-29). The difference between “religion” and the gospel is that religion gives burdens by announcing that Jesus plus something equals everything while the gospel absorbs burdens announcing that Jesus plus nothing equals everything.
Read the whole post (and get a bit of context, if you need it) here.