It seems that in 200 AD, while missionaries were still working hard to spread Christianity, Saxons were holding a festival honoring their goddess, "Eastre", and celebrating children and the coming of spring. Sound familiar? (except the goddess part, of course). Anyway, in any effort to win them over to Christianity, and since the festival coincided with the Christian celebration of the birth of Christ, the early missionaries sort of snuck in the idea of Christianity over time as they celebrated with the Saxons. Ultimately, the name "Easter" was taken for the holiday.
For a more in depth treatment of the subject, please see Arlene Wright - Correll's blog @ http://www.phancypages.com/newsletter/ZNewsletter2599.htm.