The Catholic Church is the Church of Christ. It is the Church He promised to build on Peter. The Episcopal Church is a break off from the Anglican Church (which was done shortly after the American Revolution because Anglicans had to pledge allegiance to the British monarch, who is head of the Anglican Church.) The Anglican Church (Church of England) was created when King Henry VIII broke off from the Catholic Church to form his own church. He did this because the Pope refused to grant him an annulment from his wife (Catherine of Aragorn) so he could marry Anne Boleyn (whom Henry later had executed so he could marry another woman).
As such when he broke ties with the Pope, the Church of England broke ties with the Church that Christ built. And it was all over one man and his wish to marry another woman.
When the Anglicans broke with the Pope and the Catholic Church, they lost their contact and communion with the promise from Christ that He would send the Holy Spirit to guide them into ALL truth. This promise is only to the Catholic Church. So when you wonder why the theological positions of your denomination keep changing, or keep getting more and more liberal, it is because they have no protection of the Holy Spirit into all truth, and the personal preferences of the leaders of the denomination are coming through.
The Catholic Church has the Fullness of Truth. Some Christian denominations have quite a bit of truth, some have very little, but none have the Fullness of Truth that the Catholic Church possesses.
(FYI, I was raised in the Baptist Church growing up.)