The accumulated scientific knowledge of Antiquity was preserved in Europe during the Dark Ages by Catholic monasteries, quite possibly hastening the advent of the Modern Age by reducing the scientific regression caused by the Fall of Rome. At least one Pope actively encouraged learning and quite possibly introduced the Arabic numeral system to Europe. During the Middle and early Modern Ages monasteries were centers of literary and scientific achievement; as late as the 19th century priests were overrepresented among great discoverers and inventors. The suppression of science by the Church has been overhyped and exaggerated by anti-religious polemics; the idea of geocentrism was widely accepted by secular scientists during Galileo Galilei's lifetime, and in any case it ultimately was ineffective in halting the spread of heliocentric doctrine. Today, Pope Francis is an advocate for peace and human rights, a role that many of his recent predecessors have served in. The Crusades, while brutal, served to widen the buffer between Islam and Christiandom and perhaps delay Islamic expansion into the European continent for several centuries, until the time when Europe was advanced enough to effectively back. Had Europe fallen to Islam, modernity probably would've never happened. Most importantly, the Catholic Church christianized Europe, allowing perhaps hundreds of millions of people to come to a saving knowledge of Jesus Christ, go to Heaven, and avoid Hell.
I believe Christianity isn't yet fully understood. One factor is how the law is stated (Matthew 22:36-40) but in regards to Catholicism what I see it offering is "Symbol and Symbolic" through the mass.
I believe that with the many inspiring individuals that have been Catholics - such as the Von Trapp Family Singers, Oskar Schindler, J. R. R. Tolkien, G. K. Chesterton, Joan of Arc and St Francis of Assisi - and the way that the Catholic church emphasizes prayer, The main effect has been positive. I also like the fact that there are monasteries and convents with monks and nuns who pray for humanity and the Church. I wouldn't want to be a nun myself but I admire them for what they contribute.
Look at catholic countries.
I mean, now they are better than they were years before, don't get that twisted. My idea of Catholics is that they changed their religion to fit paganist cultures, which changed the religion a lot. Along with that, they had a lot of corruption in the past, which is the most important part of my reasoning, not the changing of the religion/culture. Anyway, corruption was bad, because it had people pay for forgiveness at some point of time, and also pay for never ending life with jesus, which wouldn't work, even in Catholic belief. That's when the Protestant revolt started, since Martin Luther didn't believe in the Catholic Churches idea of payment equals blessing. So he and many other people for several years started branching off from the corrupt version of the Church, not to get mixed up with the older christians that branched off from the Earliest Church, but that's a different story that I don't want to talk about. Anyways, years past and now the Church is a lot more better than they were hundreds of hundreds of years ago. Even with that, I don't agree with some things they still do and believe, that doesn't make an effect of bad or good very much. So if you're asking throughout all time, than they're negative since of corruption, but not of the Crusades, since it was about stopping the Muslim groups from invading the European Christian countries. But if you mean right now, than they are positive, since they are spreading peace and love, and not as corrupt as they were before.
There is a great video on YouTube of an episode of an Intelligence Squared debate between Christopher Hitchens/Stephen Fry and Archbishop John Onaiyekan/Ann Widdecombe. Aside from this debate, what I can say from my personal experience is that everything that a catholic does and claims is proof of the goodness of the catholic church... can be done without the overarching religious context. Giving to people can be done without a religious institution backing the idea. Helping people in need can be done without religion. Creating a community and supporting others can be done without religion. The benefits that people claim come from being a catholic can all be done without being catholic. So what benefit does being a catholic truly have? The morality and teachings of the bible come from a very hand picked version that people with a humanist perspective have selected, while ignoring non-humanist teachings such as having slaves or dominating women, etc.
negative scriptural wise and historical. I wouldn't even call them christians because they don't believe in grace according to the bible and have to make prayers. Also they pray to saints and venerate the dead. Idolatry in a word.