Considered by many to be the "Catholic Luther" (as opposed to Luther being the Lutheran Canisius I guess), Peter created a reform movement in the Church which spread throughout Southern Germany. His patience and humility should guide us today, not just with those who believe differently or are lax in their Faith, but with everyone with whom we disagree on all range and matters of subjects. I can say that I am probably a direct beneficiary of his charity, diligence, and sound theological teachings.
It is plainly wrong to meet non-Catholics with bitterness or to treat them with discourtesy. For this is nothing else than the reverse of Christ’s example because it breaks the bruised reed and quenches the smoking flax. We ought to instruct with meekness those whom heresy has made bitter and suspicious, and has estranged from orthodox Catholics, especially from our fellow Jesuits. Thus, by whole-hearted charity and good will we may win them over to us in the Lord.
Again, it is a mistaken policy to behave in a contentious fashion and to start disputes about matters of belief with argumentative people who are disposed by their very natures to wrangling. Indeed, the fact of their being so constituted is a reason the more why such people should be attracted and won to the simplicity of the faith as much by example as by argument.
-- From a letter to his superior