As I said in the comments of “more a monk than anyone I know”, Victor and Merton expressed themselves in different ways, artistically, and had difficulty appreciating the style of the other.
Victor Hammer was classical and refused to be carried away by contemporary fashion. Merton’s art was abstract, different.
Merton was especially sensitive to how Victor would react to his art when it was exhibited in Louisville, and he did not invite the Hammers to a private viewing that was held for special friends. The only comment Victor gave Merton about the calligraphies was: "It is a mad world we live in and I am afraid you are not fully aware of it with the things you draw as an artist. Or are you?"
Yet the extreme graciousness with which these friends carried their differences within a context of the highest respect and unlimited love for each other is remarkable. Merton treasured Victor's friendship and visits, which were reassuring and stabilizing: “We belonged together”. (Learning to Love, p.270)
The other is that Victor Hammer was what some people call an “unbeliever”. Though he was Catholic by birth, he distrusted the Church and no longer practiced his faith within the context of Church. He died in July 1967, refusing the Sacraments.
Merton referred to Victor as “a very believing ‘unbeliever’” – one whose distrust of Church is part of a deeper belief - and it was compassion for him, in part, that prompted the essay “Apology for an Unbeliever”. Here is an excerpt from that essay:
"At this point I am making a public renunciation, in my own name at least, of all tactical, clerical, apologetic designs upon the sincerity of your unbelief. . . I think this apology is demanded by the respect I have for my own faith. If I, as a Christian, believe that my first duty is to love and respect my fellow in his personal frailty and perplexity, in his own unique hazard and need for trust, then I think that the refusal to let him alone, to entrust him to God and his conscience, and the insistence on rejecting them as persons until they agree with me, is simply a sign that my own faith is inadequate.
"My own peculiar task in my Church and in my world has been that of the solitary explorer who, instead of jumping on all the latest bandwagons at once, is bound to search the existential depths of faith in its silences, its ambiguities, and in those certainties which lie deeper than the bottom of anxiety. In these depths there are no easy answers, no pat solutions to anything. It is a kind of submarine life in which faith sometimes mysteriously takes on the aspect of doubt, when, in fact, one has to doubt and reject conventional and superstitious surrogates that have taken the place of faith. On this level, the division between believer and unbeliever ceases to be so crystal clear. It is not that some are all right and others all wrong: all are bound to seek in honest perplexity. Everybody is an unbeliever more or less."
- From "Apologies to an Unbeliever" by Thomas Merton