Aha, I have another suggestion for the OP. Check into your diocese and see if they have an office of Youth Protection or Safe Environment or similar. Perhaps this is peculiar to dioceses in the United States, which set up these offices after the abuse scandals threatened to bankrupt many of them. But check their website, and if it is not obvious there, I would put in a call to your chancery office, remain anonymous if you need to. Ask there if they have someone in charge of sexual abuse reports. Find out information from them about how to deal with such a case.
So far, from the information you have given this, the person is only targeting adults with his talk. It is possible that he has revealed his “differing opinions” to the children, but he is not making passes at them, and this is good. I hope and pray that he stays away from children if he knows what is good for him. Make sure to stress this fact when speaking to the diocesan office. This is sexual harrassment between adults, which is a different matter than that involving minors or vulnerable adults. I am speaking here from experience in Safe Environment Training, provided by my diocese.
Of course, this depends on whether your school is an official part of the diocese. You say it is a Catholic school so I am assuming here that it is, either attached to a parish, or part of the diocese and subject to its rules and regulations. Check the diocesan website and it will tell you. I will pray for you.