Father Mille lived and ministered in Switzerland in areas of mixed religion, and where some of the Protestants were strongly anti-Catholic. Eugene encourages discretion in the approach of the Oblates.
I think Father Guibert has written you that he thinks it would do Father Hermite good to go out occasionally on a mission. He must have given you his advice about the leader you would be well-advised to name. Whoever it is, I urge him to be very prudent in the matter.
This is especially necessary in the mixed localities that you evangelise. Don’t direct your efforts to converting Protestants. All the better for them if they profit from our passage, but don’t have them particularly in mind, the private good could be at the expense of the common good: what is more, you are sent ad domesticos fidei. Organize yourselves on that basis. It wouldn’t take much to unleash a persecution whose consequences would be incalculable.
Letter to Jean Baptiste Mille, 15 January 1835, EO VIII n 501