What Is a Non-Catholic?
The simple answer is that a non-Catholics is anyone who is not a Catholic. This is the opposite to what is a Catholic? Some may object that this discussion is in the wrong folder, and in part you are right. Un-Baptized People
All unbaptized people are non-Catholic, including Catechumens. However, Catechumens can receive Baptism of desire and if they die prior to Baptism are still given ecclesiastical burial. Included, then are the Islam, Hindus, Buddhists, Shinto, Pagans, Atheists, Communists, etc. The Church opens her arms to all of these and wishes they would come to a knowledge of the truth, as Jesus wishes all to do. Baptized Non-Catholics
This group is divided into two classes. The first, like their unbaptized brethren, are ignorant of the true Faith and have been raised in a non-Catholics sect, which observes a valid Baptismal rite. The second group have once been part of the Catholic Church and have abandoned her. Baptized Outside the Catholic Church
Here we include the Orthodox, the Anglicans, the Old-Catholics and some Protestants. Some Protestant sects have valid Baptism, others invliad and still otehrs are doutful due to lack of proper form, intention or a doubtful belief of the prupose of the Sacrament of Baptism. The Church also welcomes all of these to come into the true Church of Jesus Christ. Techincally all who have been Baptized and who have adhered to a non-Catholci sect are considered heretics. However, there is a major difference. Those who have been baptized in the Catholic Church and have deserted her are considered in more daner and in some cases their salvation is despaired of, because they have made a willful decision to desert the true Faith. In this time of confusion, though, few are considered as willful heretics, for most have been deceived by the various non-Catholcis sects, such as the Traditionalists and the Pog Church of Vatican II. The Church oepns her arms to receive all into the true Church of Jesus Christ. The same requirements are made for all those who have been baptiuzed and have been in a non-Catholcis sect, that is rejeciton of said sect and its schism and heresies; profession of the true Faith, and finally absolution from the excommunication for heresy which may have been incurred. 
Michael Fighting
