Are you kidding? How does Christmas being December 25th and Easter "moving round" in anyway prove or disprove if "catholicism is real?" Sorry I don't get what point you are trying to make. Is it just a slam to the Catholics? You know, all Christians celebrate Christmas and Easter on the same days, even though Easter "moves round with no set date." Do yourself a favor and google "Christianity" you'll find more than you ever imagined to help you understand.

there is a real calender and a religious calender that is why easter bounces around.

Easter technically does have a set date. Its the first sunday after the first full moon after after spring equinox

The holidays are set by man and man is indecisive. [Note: this isn't aimed at chocolate milk] Technically, the term 'catholicism' extends to the whole of Christianity and not just the Vatican

Just a suggestion read "The Two Babylons" by Rev Alexander Hislop , this book explains the origins of Christmas and Easter. He's a very respected author, historians choice.

Why would that prove or disprove the validity of a religious group? Neither are matters of doctrine for any Christian faith. Christmas is a set, arbitrary date that no one claims is the actual birthday of Jesus. Easter is based upon something other than the Gregorian calendar (all calendars are arbitrary human inventions) and is the best guess of people as to the best time to commemorate the Passion.

The holiday can be anytime from two days to 31 days after the first full moon of spring. The reason for that is that in the early Church, Easter was celebrated in accord with the rules for the Jewish Passover holiday. The Bible records Christ’s resurrection as the Sunday following the Passover. So, Easter Sunday was the Sunday after Passover. The problem, though, is that Passover is computed using the Jewish calendar, and the Jewish calendar is a luni-solar calendar. That is a calendar that is based on the phases of the Moon, with months starting with the New Moon, but also in accord with the Sun, with the year relative to the equinox. The problem is that the month of the passover is difficult to compute far in advance. In fact, it was almost incalculable in the days of the early days of Christianity. As a result, different churches were celebrating Easter on different dates. Setting a uniform set of rules for computing Easter was one of the many tasks of the First Council of Nicaea. The rules for determining Easter separated the celebration of Easter from the Jewish Passover, but those rules normally result in Easter in being celebrated at about the same time as Passover. Those rules are a bit complex, but they can be summarized as approximately saying that Easter is the Sunday following the Full Moon on or after March 21. This is close to the date of Passover because the Hebrew calendar defines Passover to start on the 15th day of Nisan, the first year of the Hebrew Calendar, which must begin with the last New Moon before the Vernal Equinox. Note that this is about the seventh month of the commonly accepted civil Jewish calendar, which starts near the Autumnal Equinox. The Vernal Equinox is supposed to be about March 21. But, the calendar does not exactly match the motion of the Earth around the Sun, so the Vernal Equinox does not always occur on March 21. This year, for example, the equinox was on March 20 (or March 19 for those living in time zones west of here). Actual determination of the equinox to high precision long ahead of time is possible today, but that was not the case close to 2000 years ago. So, to keep everyone on the same page, the decision was to simply define the Vernal Equinox as March 21 in the ecclesiastical calendar. But, that still didn’t alleviate all confusion. It is sometimes difficult for non-astronomers to determine the exact moment of the Full Moon.

What does that have to do with "catholicism" being "real" or not???????? . Easter has to be on Sunday always.. not every easter sunday with be the same date. Christmas is a celebration of a birthday, which should be the same date every year. In this case it's Dec 25th.