First of all how can you be a devout Catholic and then leave the Catholic Church?

Makes no sense to me.
Devout means devoted to ,as to its faith and practices ,and yes loyalty.This is the opposite of a Catholic in name only ,not really practicing or believing ,and maybe ignorant of teaching. Both types have left the church ,and found spiritual life in “other” churches .I would think you personally know people who fit these 2 scenarios (there are more). Would you say a nun or priest is a devout Catholic ? Most would say yeah , they have given there lives to Christ and His church -they are at least devout. What I was saying is that while in that Catholic station ,they somehow come to believe different interpretation of things , usually some parts of scripture, and ponder them , while still serving Christ and His church. They begin to interpret differently what it means to serve Christ, and what it means to be loyal to his church , even what is really his Church etc. At some point they leave the church .I have been told they become a “fallen” catholic.
Secondly how can you blame the Church for the sins of others.
How can I blame your church when I do not view it as a sin that they listen to God also ,as they were taught to as Catholics ? I am just trying to say you can not blame Protetsantism ,or Sola Scriptura ,or a million other things when Catholics themselves get different interpretations, as Catholics.You can blame those things if a Catholic falls away from Catholicism (no longer devout or practicing) for whatever reason ,then years later they listen to “Luther “. Yes, blame” Luther”,SS etc. then. Don’t blame them when a nun simply reads her Catholic bible, or in meditation, comes to a different “light”–reading or listening to nothing of protestantism.
Next this one really blows my mind. How could the Pope cause division in other Churchs? And these other Church’s that have Apostolic Succession where did it come from? There was more then One Apostolic succession? Please show me this information.
Let me try again .Division here is of a different sense .Perhaps a better word is discord or friction ,where ther was none before .In fact there was division before with no discord or friction(kind of live and let live attitude ,tolerant ,because the two dates may both have been apostolic.The eastern date(more jewish) is attested to by Polycarp ,disciple of John.Maybe the western date (sunday is attributed to Paul -gentiles ) For 150 years both dates were celebrated in respective regions, by respective peoples and -peacefully.The Pope (Victor 190) decreed that in at least Rome, all had to celebrate it on Sunday, even eastern church immigrants living in Rome .To say the least the easterners did not like this change from their apostolic heritage on this issue. All I am saying is that the pope could have left it alone,as had previous popes ,and as several bishops suggested ,to no avail (most bishops preferred Sunday). Anyways several have posted a site you can go to for a rather honest depiction on this history. See post 795, kindly provided by PRmerger.
Tell me when do you say the Pope CAME ALONG? What year would you say he appeared.
Iraneus I believe he had the first list of bishops of Rome ,and listed Peter and Paul as the first.