Q. 1. What is a sedevacantist?
A. 1. A sedevatist is a Catholic who belongs to a schismatic movement, therefore having removed himself from full communion with the Church, by refusing to acknowledge the authority of the Pope(s) based on his personal opinion as to who is really the Pope.
# 751 of the Code of Canon Law states that those who refuse to submit themselves to the authority of the Pope or to be in communion with the members of the Catholic Church under his authority, they are classified as schismatic.
"Can. 751 Heresy is the obstinate denial or obstinate doubt after the reception of baptism of some truth which is to be believed by divine and Catholic faith; apostasy is the total repudiation of the Christian faith; schism is the refusal of submission to the Supreme Pontiff or of communion with the members of the Church subject to him."
Sedevacantists are identified by their beliefs that could be any of the following, such being a partial list of their kind:
• There has been no Pope since Pius XII died in 1958;
• Pope John Paul II was an imposter Pope;
• Pope John Paul II was an usurper and anti-Pope;
• Pope Benedict XVI was/is a heretic, etc...
Catholics are advised not to associate themselves with any type of group that denies the authority of the Pope.