Interestlingly, the distiguished commentators were not very partial to dialogue and encounter with our in-house heretics:
Don't kill the heretics...
Chrys.: This the Lord spake to forbid any putting to death. For we ought not to kill an heretic, seeing that so a neverending war would be introduced into the world; and therefore He says, “Lest ye root out with them the wheat also;
Jerome: ... room for repentance is left, and we are warned that we should not hastily cut off a brother, since one who is today corrupted with an erroneous dogma, may grow wiser tomorrow, and begin to defend the truth...
Aug., Quaest. in Matt., q. 12: ... [and] because good while yet weak, have need in some things of being mixed up with bad, either that they may be proved by their means, or that by comparison with them they may be greatly stimulated and drawn to a better course.
... but limit their freedom of speech, break their synods and anathematize them.
Chrys.: Hereby He does not indeed forbid all restraint upon heretics, that their freedom of speech should be cut off, that their synods and their confessions should be broken up—but only forbids that they should be put to death.
Aug., Cont. Ep. Parm., iii. 2: For when any one of the number of Christians included in the Church is found in such sin as to incur an anathema, this is done, where danger of schism is not apprehended, with tenderness, not for his rooting out, but for his correction. ... when that fear has ceased, and when the safety of the crop is certain, that is, when the crime is known to all, and is acknowledged as so execrable as to have no defenders, or not such as might cause any fear of a schism, then severity of discipline does not sleep, and its correction of error is so much the more efficacious as the observance of love had been more careful.
Unfortunatelly, ous pastors failed to heed the wise counsel of the Fathers and we ended up in our current predicament.
If necessary follow the example of Jesus and use force (it's for their own good and it may save many).
Aug., Ep. 93, 17: This indeed was at first my own opinion, that no man was to be driven by force into the unity of Christ; but he was to be led by discourse, contended with in controversy, and overcome by argument, that we might not have men feigning themselves to be Catholics whom we knew to be declared heretics. But this opinion of mine was overcome not by the authority of those who contradicted me, but by the examples of those that shewed it in fact; for the tenor of those laws in enacting which Princes serve the Lord in fear, has had such good effect, that already some say, This we desired long ago; but now thanks be to God who has made the occasion for us, and has cut off our pleas of delay...let the the kings of the earth shew themselves the servants of Christ by publishing laws in Christ’s behalf.
Aug., Ep. 185, 32 et 22: ... our Catholic mother the Church, when by the loss of a few she gains many, soothes the sorrow of her motherly heart, healing it by the deliverance of so many people. Where then is that which those are accustomed to cry out, That it is free to all to believe? Whom hath Christ done violence to? Whom hath He compelled? Let them take the Apostle Paul; let them acknowledge in him Christ first compelling and afterwards teaching; first smiting and afterwards comforting. And it is wonderful to see him who entered into the Gospel by the force of a bodily infliction labouring therein more than all those who are called by word only. [margin note: 1 Cor 15:10]
Why then should not the Church constrain her lost sons to return to her, when her lost sons constrained others to perish?