Friendship with Nietzsche

'How Christian is Our Present-Day Theology?' was published at the same time as the first of Nietzsche's 'The Untimely Meditations'. Both writings were critical of David Strauss and shared similar main theses. Although these were the only books Nietzsche and Overbeck published together, theses similar to Overbeck's can be found in Nietzsche's writings through 'The Antichrist'.
After Nietzsche left Basel in 1879, he and Overbeck continued a personal friendship through regular correspondence. In a letter from 1881, Nietzsche wrote to Overbeck:
My dear friend, what is this our life? A boat that swims in the sea, and all one knows for certain about it is that one day it will capsize. Here we are, two good old boats that have been faithful neighbors, and above all your hand has done its best to keep me from 'capsizing'! Let us then continue our voyage -- each for the other's sake, for a long time yet, a long time! We should miss each other so much! Tolerably calm seas and good winds and above all sun -- what I wish for myself, I wish for you, too, and am sorry that my gratitude can find expression only in such a wish and has no influence at all on wind or weather.
At the beginning of January 1889, Nietzsche sent letters to friends that exhibited symptoms of a mental collapse. After Overbeck received such a letter, he travelled to Turin the same day to retrieve the sick Nietzsche and his manuscripts. He continued to visit Nietzsche until the latter's death in 1900.
To remain sincere to his friend, Overbeck maintained a critical distance from the content of Nietzsche's writings, and denounced the beginnings of a hero-worship and revisionism. He refused to cooperate with Elisabeth Förster-Nietzsche and her Nietzsche-Archiv and, mostly in private notes and letters, accused her of misinterpreting Nietzsche. He refused to give her his correspondence with Nietzsche - which turned out to be right, as she would forge other correspondents' letters.