It seems hard to understand at times. Even for one who strives to own a proper Biblical attitude toward others.
Mike recently spoke with one of his professors on such a topic. The professors response was that it's because they (miserable-feeling Christians) have once tasted the sweetness of Christ and know they are no longer living in fellowship with the supplier of that great sweetness.
In the book I'm currently reading, I came across a quote by Amy Carmichael that seems to support that same idea:
If we would walk with an ungrieved Lord we must never let the fear of being thought "hard" or, far more subtle temptation, the fear of pain for a younger one whom we love, cause us to influence that one to choose the natural rather than the spiritual. If once a soul has entered the path where the Spirit, not the flesh, is guide, God does not lightly pass over such a lapse. Men may praise it; God condemns it; and those who know their Father know the bitterness of the hiding of His face.I believe it's the moment we hide His face, that we find misery. And thus, we feel, the whole world should partake in such a state.
When you come across a miserable Christian, do not be tempted to believe it is you who has caused their contempt. It is their own choosing. And to walk with the Lord, in front of them, with a fast and strong stride, reminds them of the sweetness that now barely still lingers on their bitter, backslidden lips.
Oh taste and see that the Lord is good!