What of the phrase, ". . . let us err on the side of grace . . ." ? This is commonplace among decisions among Christians, most notably within churches and parachurch organizations. It sounds good, since we are people who have experienced grace and have had the opportunity to 'embrace grace' (HT: McK). And, I suppose that 'to err is human . . .' so there is real and powerful logic behind the sentiment.
Except for the nagging bit that we are also supposed to be people of the truth, which clearly dictates that some things are right and some things are wrong. The balance which must be struck between truth and grace does not allow us to simply err on the side of grace as though its primary purpose is to cover our lack of diligence. Is this concept not similar to the notion that it is easier to ask for forgiveness than it is to ask permission? This phrase, no matter how much it may capture real-life drama, leads people to focus solely on forgiveness and not on right character. Yes, it is 'easier' to find forgiveness before God . . . but it is 'right' to seek his permission and guidance.
The same is true for erring on grace's side of the table. Does our God not prefer that we not err at all? Is it perhaps simply easier to get it wrong under the smothering of our own perception of grace than to seek and ponder and pray and wait upon him for the right direction?
In the end, I must confess that I do agree that any errors in our human judgment - those times when our own hearts and minds cloud out the presence of the divine Spirit - should fall on the side of grace before they fall on the side of judgment. But it is far, far greater that we should be people of the Book, people of the Spirit, people of the Christ and know what we believe, why we believe it and how it is called to work out into the world.
The primary barrier to this will always be individuals who are unwilling to commit to the high demands of discipleship. Until then, erring will certainly multiply.