The idea that we should only celebrate the Old Testament Feasts is not Biblical. In fact the Bible says not too judge anyone on account of what days they celebrate.
Romans 14:5-6 (NIV2011)
5 One person considers one day more sacred than another; another considers every day alike. Each of them should be fully convinced in their own mind.
6 Whoever regards one day as special does so to the Lord. Whoever eats meat does so to the Lord, for they give thanks to God; and whoever abstains does so to the Lord and gives thanks to God.
Deuteronomy 12:30 Take heed to thyself that thou be not snared by following them, after that they be destroyed from before thee; and that thou enquire not after their gods, saying, How did these nations serve their gods? even so will I do likewise. 31 Thou shalt not do so unto the LORD thy God
The Catholic Church incorporated many pagan practices and feast days to attract them into their church. The admit that themselves.