Your Baha’i brother probably gained his negative (and I would say erroneous) understanding of Catholic Church history from reading Some Answered Questions by Abdu’l-Baha, in which one will find this:
"…let us compare the lives of some of the Popes with the religion of Christ. Christ, hungry and without shelter, ate herbs in the wilderness, and was unwilling to 136 hurt the feelings of anyone. The Pope sits in a carriage covered with gold and passes his time in the utmost splendor, amidst such pleasures and luxuries, such riches and adoration, as kings have never had.
Christ hurt no one, but some of the Popes killed innocent people: refer to history. How much blood the Popes have shed merely to retain temporal power! For mere differences of opinion they arrested, imprisoned and slew thousands of the servants of the world of humanity and learned men who had discovered the secrets of nature. To what a degree they opposed the truth!
Reflect upon the instructions of Christ, and investigate the habits and customs of the Popes. Consider: is there any resemblance between the instructions of Christ and the manner of government of the Popes? We do not like to criticize, but the history of the Vatican is very extraordinary. The purport of our argument is this, that the instructions of Christ are one thing, and the manner of the Papal government is quite another; they do not agree. See how many Protestants have been killed by the order of the Popes, how many tyrannies and oppressions have been countenanced, and how many punishments and tortures have been inflicted! Can any of the sweet fragrances of Christ be detected in these actions? No! in the name of God! These people did not obey Christ, while Saint Barbara, whose picture is before us, did obey Christ, and followed in His footsteps, and put His commands into practice. Among the Popes there are also some blessed souls who followed in the footsteps of Christ, particularly in the first centuries of the Christian era when temporal things were lacking and the tests of God were severe. But when they came into possession of governmental power, and worldly honor and prosperity were gained, the Papal government entirely forgot Christ and was occupied with temporal power, grandeur, comfort and luxuries. It killed people, opposed the diffusion of learning, tormented the 137 men of science, obstructed the light of knowledge, and gave the order to slay and to pillage. Thousands of souls, men of science and learning, and sinless ones, perished in the prisons of Rome. With all these proceedings and actions, how can the Vicarship of Christ be believed in?
The Papal See has constantly opposed knowledge; even in Europe it is admitted that religion is the opponent of science, and that science is the destroyer of the foundations of religion…"
This is a complete misunderstanding of Catholic history and the Catholic Church’s relationship with science. However it is easily refuted if one closely studies history from modern un-biased sources which to be fair, Abdu’l-Baha did not have at hand when he said this. The sad thing nonetheless is that despite Abdu’l-Baha’s good intentions, Baha’is believe the above to be divinely inspired, which is probably why your brother is so adamant that Catholic history is so dire. However, some Baha’is will probably recognize that Abdu’l-Baha was infallible - from their perspective - only in terms of moral and doctrinal truth, and not in history, and so will be open to the idea that he got some historical facts wrong, as a result of the relatively biased histories of the time, which he surely must have consulted.
In truth the rational theology of the Catholic Church in the Middle Ages led directly to the discoveries of modern science.
As Thomas E. Woods, Jr. explained, despite the widely held conception of the Catholic Church as being anti-science, this conventional wisdom has been the subject of “drastic revision” by historians of science over the last 50 years. Woods asserts that the mainstream view now is that the “Church [has] played a positive role in the development of science … even if this new consensus has not yet managed to trickle down to the general public”.
The Baha’i Faith also has a lot of positive, nice things to say about Catholicism:
"The Guardian agrees with you that the Bahá’ís should be very careful not to criticize or rather attack the [Catholic] Church. As we believe the Church of Rome to be the inheritor, so to speak, of Christ’s teachings, the direct line, however perverted by men’s doctrines, it certainly does not befit us to show antagonism towards it. We know it is out-dated. Tact is required!"
(From a letter written on behalf of Shoghi Effendi to an individual believer, March 22, 1950)
"A Catholic background is an excellent introduction to the Faith, and one that Mrs. … should feel gratified for having had. Though doctrines of the church today are no longer needed – as the Father Himself has come, and thus fulfilled the mission of Christ the Son yet the foundation they lay of spiritual discipline, and their emphasis on spiritual values and adherence to moral laws, is very important and very close to our own beliefs." *(From a letter written on behalf of the Guardian to two believers, August 17, 1941; Compilations, Lights of Guidance, p. 491) *
Directives from the Guardian: 107 JESUS (Virgin Birth of)
"With regard to your question concerning the Virgin Birth of Jesus; on this point, as on several others, the Baha’i teachings are in full agreement with the doctrines of the Catholic Church."
, and often participates in interfaith studies and activities, even going to Lenten reflections with my mom in the Catholic church. He’s now upset that his future wife’s Christian church can’t be as flexible as the Baha’i faith in an interfaith marriage, and thinks it’s a level of ignorance on the part of the pastor that won’t allow the two-faith ceremony. And, despite his superior intelligence in his theological studies (
), he’s a peaceful gentle soul and would never interfere with his future wife’s faith journey.