What exactly are you disagreeing with? I said Christians didn't adopt the pagan holidays, and they clearly didn't. Christians began holding Christian celebrations on the same dates as pagan holidays for pragmatic reasons. For Christians to adopt the pagan holidays they would have to celebrate those holidays in the same way the pagans did and for the same reasons. Clearly that didn't happen.
Re-read your own preferred definition:"Adopt | Definition of Adopt by Merriam-Webster http://www.merriam-webster.com/dicti...ctionary/adopt adopt, embrace, espouse mean to take an opinion, policy, or practice as one's own. adopt implies accepting something created by another or foreign to one's nature."
Did the Christians "take an opinion, policy, or practice as one's own...accepting something created by another or foreign to one's nature."? Absolutely not! They rejected paganism and scheduled Christian Holy Days on the same dates as pagan holidays to compete against the pagan festivals and to make their own activities less visible.
TT said "I was just reading how Easter was originally a pagan holiday and then adopted by other religions." That statement is totally untrue. Various pagan beliefs and practices did bit by bit creep into other religions, especially among people who were forced to convert, but that's a far cry from claiming that Easter was created by pagans and adopted by other religions.
Easter, as a Christian religious observance, is based on the New Testament story that Jesus was crucified just before Passover and rose just after it. So if Christians "adopted" Easter at all, they adopted it from the Jews, which isn't really an adoption since most of the early Christians were Jews.