It’s probably unarguable that the dates of Christian festivals were linked with the dates of earlier festivals of pre-Christian belief-systems.
What is harder to pin down is any certainty about individual deities of those early times. However, it’s interesting to look at what has been and/or still is believed about them.
Eostre’s most familiar description is of a Germanic Fertility Goddess, with the alternative names Ēostre, Ostara, and Eastre. She is a spring goddess
and has her own festival on 21 March, the Spring Equinox.
Her association with renewal and rebirth goes far to explain the links she seems to have with eggs and rabbits (or hares). It also seems to make her a reasonable link for the Celtic church to choose for the central Christian beliefs about crucifixion and resurrection.
Rabbits and hares are found in many mythologies and are often tricksters; in connection with Easter, however, it’s easy to see that the main link is their prolific nature and contribution to the replenishing of life in the spring.
‘Love is come again like wheat that springs up green.’
Three Running Hares (c) Sue Wookey