Perhaps the two of the most effective enemies of the gospel within the Church in North America are the twins: Moralism and Legalism. While there are other enemies at work, such as Relativism and Licentiousness, these are far more obvious in their opposition to the gospel. Moralism and Legalism, however, are so potent, especially among conservatives, because they stealthily fly under the radar. In fact, they are such subversives that they are often embraced as if they are part of the gospel, or at least partners with it.
Here is something Tim Keller offers to combat these sneaky, deadly foes:
Some claim that to constantly be striking a ‘note of grace, grace, grace’ in our sermons is not helpful in our culture today.
The objection goes like this: “Surely Phariseeism and moralism is not a problem in our culture today. Rather, our problem is license and antinomianism. People lack a sense of right or wrong. It is ‘carrying coal to Newcastle’ to talk about grace all the time to postmodern people.”
But I don’t believe that’s the case. Unless you point to the ‘good news’ of grace, people won’t even be able to bear the ‘bad news’ of God’s judgment. Also, unless you critique moralism, many irreligious people won’t know the difference between moralism and what you’re offering.
The way to get antinomians to move away from lawlessness is to distinguish the gospel from legalism. Why? Because modern and post-modern people have been rejecting Christianity for years thinking that it was indistinguishable from moralism. Non-Christians will always automatically hear gospel presentations as appeals to become moral and religious, unless in your preaching you use the good news of grace to deconstruct legalism. Only if you show them there’s a difference–that what they really rejected wasn’t real Christianity at all–will they even begin to consider Christianity.