What is Thomas Aquinas' perspective on salvation for baptized heretics who believe in the Trinity?

St. Thomas Aquinas is praised globally for his intellect, and such has gained him the merit of being a 'Doctor of the Church'. I am curious about several things though: 1. What are Aquinas's views on what is necessary for the attainment of salvation for the individual? 2. What are Aquinas's views on the nature of moral accountability for heretical opinion and action? 3. How do these views correspond to his view on heretics who are like-minded and like-spirited to the Church in more central matters, such as belief in the Trinity and the upholding of the Sacrament of Baptism? Modern heretics nowadays akin to this category would include the Roman Catholic Church's separated brethren, being Protestants and even more so Orthodox Christians. If Aquinas is silent about this matter, what would be the logical deduction one could make about his views regarding the salvation for baptized heretics who accept the Trinity taking into account his views on the two previous topics? *Note that I am not using the word 'heretic' here in a malicious way but rather in the way that is most useful given the context. The Roman Catholic Church, along with Aquinas, considers those outside of her to be 'heretics', and that is the intended meaning here. This language was used in order to better qualify the views of he who this question is about, being Thomas Aquinas.