For those here who are Orthodox Christians or interested in Orthodox Christianity - Christ is Risen!
In Orthodox Christianity, this is the greatest Holiday, greater and more important than even Christmas. Everyone have a birthday, and everyone will meet Death, but it was Christ who defeated Death and show that it is not the end. That's what we celebrate today.
PS: And also, by occasion, we here in Russia celebrate first man in space too. Gagarin was not religious, at least openly, but he was baptised in Orthodox Christianity in childhood and grew in faithful and traditional peasants family.
I fully support my Orthodox brothers in Christ, but with all due respect to them, they need to get their liturgical schedule on the Gregorian calendar and the whole world can celebrate Easter at the same time.
Of all the petty things stemming from the Great Schism, this is the pettiest.
Christ Ressurection happened after Jewish Passover.
Thre is many layers of sense here. F.e., just on the surface - Jews celebrated salvation of their first-born by spilling blood of lamb on their doors, and escape from Egypt's slavery, and at the same time they spilled blood of God's first-born who came to show them the way to escape their Satan's slavery. They made Son their sacrificial Lamb for Passover. And as soon, as this hypocritical Jewish celebrations ended, Christ had risen and show the way out of Satan's captivity to all people on Earth.
So, Christ Ressurection celebration should always be after Jewish Passover. This was established as a rule on First Nikei Ecumenic Council in 325.
We still hold to that testament, and we know why we do that.
Those who choose Gregorian calendar, obviously do that to make everyone to forgot about underlying reason.
Charitably, you have a misunderstanding of the issue.