Romans 15 (vii)

Receive your disreputable and erring brothers and put up with them patiently and take on their sins as your own. And if you have anything that is good, let it be theirs. If you think of yourselves as being better than these brothers, then do not take yourselves so seriously as if anything good could only belong to you, but, instead, humble yourselves and be like one of them so that you can carry them along with you. For it is a wretched form of justice when Christians will not put up with people they regard to be worse than they are. And you take flight from them and go into solitude instead of being of immediate use to them by your patience, prayer and good example. (...) If you are either a lily or a rose, then realise that your life must be lived among thorns. Take care that you yourself do not become a thorn on account of your intolerance and outrageous judgements or secret pride. The Kingdom of Christ is situated in the midst of His foes. What fantasies are you dreaming up then with your kingdom amidst friends?

The complete Luther - "A Meditation for Each Day of the Year" is available as a biligual (English and German) BREVIARY published by Wartburg Verlag Weimar. It can be purchased in English, world-wide from most internet book shops.