There is no usurpation. The only Savior I know is Jesus Christ and He set up one Catholic Church as the vessel of universal salvation. I know that from the scripture: in Matthew 16:18-20 Christ promised that He will build His Church for the express purpoes of opening the Heavenly Kindgom; in Acts 2:38 St. Peter urged all to come to repentance and be baptised in my Church; in 1 Peter 3:21 St. Peter directly links baptism to salvation, and it is one baptism that we believe in not several (1 Cor 12:13).
I know that many prefer to inject some allegorical sense in these verses and speak of some hypothetical invisible universal church of which the Catholic Church is but a part. But nowhere in the Holy Scripture do we see this notion supported, and in 1 Corinthians 1:10 St. Paul directly teaches that whatever distinctions exist, they should not amount to any whatsoever doctrinal disunity.
Others say that the Scripture does not describe the Catholic Church at all, not even as a part of some whole, because the seven sacraments of the Catholic Church, and the hierarchical clerical structure are not defined with precision in the Scripture. To this I say that surely the essential part of every sacrament is described in the Scripture; the primacy of Peter is described, apostolic succession of bishops is described; on the other hand it is not realistic to expect the same trappings of power and glory that we see in modern Catholic Church of a billion people, in the underground nascent Church of 1c. As far as one wishes to go in history, the writings of the Fathers of the Church describe a church that I instantly recognize as the Catholic Church I know today.
We are divided today, to be sure -- we have our separated "second lung" our beloved sister Orthodox Church that despite centuries of separation retained her original Catholic character (or is it that we retained her Orthodox character?), apostolic succession and salvific power of God.
Pride is a great sin at the root of which is denial of God. To proclaim the Gospel and to obey it as written, howbeit proudly or loudly is not a sin, it is a commandment. "He that shall be ashamed of me and of my words, of him the Son of man shall be ashamed, when he shall come in his majesty, and that of his Father, and of the holy angels"; "preach ye upon the housetops".
Your father converted to Catholicism and he dealt with it, you say, "imperfectly". Well... so did every saint except Our Lady. Ask for his prayers.
I’ll take that as a “No.” Thanks. May our Lord richly bless you and yours.