The charge is that the word “Easter” derives from the name of a pagan fertility goddess “Eostre.” It is said that Christians took over a spring festival devoted to this deity. But this article by British historian Anthony McRoy debunks that claim: Was Easter Borrowed from a Pagan Holiday? | Christian History.
Besides, English and the other Germanic languages are the only languages that calls the Festival of the Resurrection “Easter.” Everyone else calls it some version of “Pascha,” which derives from the Hebrew word for “Passover.” And the holiday was celebrated extremely early in the church’s history, evidently by the 2nd century. And its original celebration in the Middle East and around the Mediterranean sea shows no connection at all to any pagan festivals.