In Galatians we see Paul clearly tackling the dangers of legalism. But what is so scary is that the desires behind legalistic practice are so often good ones, in fact they are ones we would share. It sees a biblical principle and wants to put it into practice, and so it suggests ways of practicing the principle. That is all well and good, the problem becomes when one practice becomes the perceived outworking of that principle above all others, or is simply the only one emphasized.
Lets take for example the call to husbands to love their wives in Ephesian 5, it is an amazing call which Paul makes on husbands but what does it look like? I want to suggest that it looks like lots of different practices as the principle is applied to different marriages. There is no one over riding way to apply this. To say it is taking time out of your week to have a date night is one possible practical application but does not fully explore the call to love. There are hundreds of ways we are to obey this call and put our principle of love into practice.
But we so often pick one and seek to apply it and our thinking goes so long as I'm doing that I am obeying the principle.
A principle is a clear teaching instruction or imperative from God’s Word to us. A practice is a specific action or decision that seeks to apply that principle to our living. It is right that we who teach the bible provide examples of scriptural principles translated into practice but it must never become the practice of the principle.