Please visit the two following links in which Fr. Peter Carota devotes time to explain the history and errors of the Old Catholics:
Photo of His Holiness Pope Pius IX
The serious and long-lasting plots and efforts which the new heretics who call themselves Old Catholics use daily in your country to deceive the faithful and to tear them away from their ancient faith, urge Us, as a duty of Our supreme apostolate, to zealously devote Our paternal care and attention to protecting the spiritual welfare of our children. We are aware, and We sorrowfully deplore the fact, that these schismatics and heretics who enjoy the favor of the civil authority exercise the ministry of their wicked sect in the region of the diocese of Basel as in other regions of your country while the religious freedom of Catholics remains publicly oppressed by schismatic laws.
Deceit Characteristic of Schism
2. Having violently occupied parishes and churches with apostate priests, they have not neglected any deception or cunning to lead the children of the Catholic Church into wretched schism. Because it has always been especially characteristic of heretics and schismatics to use lies and deception, these sons of darkness are to be reckoned among those the prophet spoke of: "Woe to you deserting children who have faith in the shadow of Egypt. You have rejected the word and have hoped in trickery and rebellion." They love to deceive the unwary and the innocent and to draw them into error by deception and hypocrisy. They repeatedly state openly that they do not in the least reject the Catholic Church and its visible head but rather that they are zealous for the purity of Catholic doctrine declaring that they are the heirs of the ancient faith and the only true Catholics. But in fact they refuse to acknowledge all the divine prerogatives of the vicar of Christ on earth and do not submit to His supreme magisterium.
Condemnation of Errors
3. In order to spread their teachings more widely, We know that some of them have been appointed to teach sacred theology in the University of Bern, hoping to be able in this way to gain new followers from the Catholic youth for their wicked faction. However, We have already reproved and condemned this deplorable sect which has produced from the old store of the heretics so many errors opposed to the principal tenets of the Catholic faith. This sect overthrows the foundations of the Catholic religion, shamelessly rejects the dogmatic definitions of the Ecumenical Vatican Council, and devotes itself to the ruin of souls in so many ways. We have decreed and declared in Our letter of 21 November 1873 that those unfortunate men who belong to, adhere to, and support that sect should be considered as schismatics and separated from communion with the Church.
4. We think it is Our duty to repeat this public declaration now and to request you to preserve the unity of faith among your faithful by every possible means in accordance with your eminent zeal and your renowned virtue. For you have given notable examples of this virtue in bearing tribulations for the cause of God. You should remind them to beware of these treacherous enemies of the flock of Christ and their poisoned foods. They should totally shun their religious celebrations, their buildings, and their chairs of pestilence which they have with impunity established to transmit the sacred teachings. They should shun their writings and all contact with them. They should not have any dealings or meetings with usurping priests and apostates from the faith who dare to exercise the duties of an ecclesiastical minister without possessing a legitimate mission or any jurisdiction. They should avoid them as strangers and thieves who come only to steal, slay, and destroy. For the Church's children should consider the proper action to preserve the most precious treasure of faith, without which it is impossible to please God, as well as action calculated to achieve the goal of faith, that is the salvation of their souls, by following the straight road of justice.
Anti-Catholic Marriage Laws
5. We recognize that apart from laws which injure the divine constitution and authority of the church, others have also been promulgated there by the civil authority which are totally opposed to the canonical prescriptions dealing with Christian marriage. These laws deeply oppose the authority and the jurisdiction of the Church. We are obliged to exhort you in the Lord to explain to your faithful by suitable instructions. Recall to their minds those truths which We have often stressed in Our apostolic letters or allocutions concerning this sacrament especially on 9 and 27 September 1852. We endeavored to give them a thorough appreciation of the sanctity and the power of marriage to enable them by pious conformity to the canonical laws in this matter, to avoid the evils which affect families and human society in consequence of contempt for the sanctity of marriage.
6. We are very confident in the Lord, beloved sons, pastors, and clerics, that you, who have been ordained not only for your own sanctification and salvation but also for that of others, in face of this huge conspiracy of the unholy and of so many dangerous allurements will prove yourselves a strong comfort and help to your bishops because of your demonstrated piety and zeal. Under their leadership, you will eagerly take up the task of diligently working for the cause of God, for the Church, and for the salvation of souls. You will strengthen the powers of the faithful who stand firm, assist the weakness of those who falter, and increase daily before God the merits which you have already attained by patience, constancy, and priestly fortitude. The labors which those who act as ambassadors of Christ must sustain are very heavy at this time. But our trust should be placed in Him who has conquered the world. He helps those who labor in His name and rewards them with a crown of unfading glory in heaven.
Obedience to Lawful Authority
7. Dearly beloved faithful children who live in Switzerland, We Speak to you with paternal affection in Our concern for your salvation. You know very well how precious is the gift of the Catholic faith which God has bestowed upon you. Never spare any care, any effort to faithfully preserve that gift. Preserve safe and sound the glory of the ancient religion which you received from your ancestors. Therefore, We urge you with the greatest enthusiasm to give support strongly and constantly to your legitimate shepherds who have received a legitimate mission from this Apostolic See. They watch over your souls since they will have to account to God for them. Listen obediently to their voices and keep in mind the words of eternal truth which Jesus spoke: "Whoever is not with me is against me; whoever does not gather with me scatters." Be obedient to His teaching. Love His easy yoke. Reject energetically those of whom Our Redeemer said: "Beware of the false prophets who come to you in sheep's clothing. On the inside however they are ravening wolves." Therefore strong in the faith, resist the ancient
enemy of the human face "until the right arm of Almighty God destroys all the weapons of the devil who is allowed a certain scope of action only in order to give Christ's faithful greater glory by his defeat . . . because where truth is the teacher, divine comfort is never lacking."
Prayer for Quiet
8. We thought We should write these things to you because the duty of Our supreme ministry requires Us to deliver the universal flock of Christ from every danger of deception and to watch over its safety as well as the unity of the faith and of the Church. Therefore, since every good gift and every perfect gift comes down from above from the father of lights, We pray to Him from the bottom of Our heart that He strengthen your power in the struggle and defend you with His help and protection. May He look favorable on your country until when the errors and the counsels of the impious have been destroyed, it enjoys the tranquil peace of truth and justice. We do not neglect to implore the light from above for the wretched people who have gone astray. May they cease storing up wrath for themselves in the day of wrath and revelation of the just judgment of God. May they turn from the error of their ways while there is still time given to them for sincere repentance. Venerable brothers and dearly beloved children, join your fervent prayers of Ours to obtain mercy and find grace in suitable aid. Receive the apostolic blessing which We impart to you lovingly in the Lord from the bottom of Our heart. We grant it to each and every one of you as a pledge of our special love.
Given at Rome, at St. Peter's, on the 23rd day of March 1875, the twenty-ninth year of Our Pontificate.