Thus, the Law covenant and all related festivals came to an end from God’s standpoint at Pentecost 33 C.E. Indeed, the destruction of Jerusalem and the temple by Roman armies in 70 C.E. soon underscored that fact. (Luke 19:41-44) So even though the rededication of the temple was an important event in the history of God’s ancient people, there is no reason for Christians to commemorate Hanukkah."
They contradict themselves with this reasoning. The Society still observes old Law covenant rituals by gathering together three times a year at major assemblies.
The following is from JW.org
"JEHOVAH instructed all Israelite males to gather at Jerusalem three times a year. (Ex. 23:14-17; Lev. 23:34-36) Jesus’ adoptive father, Joseph, took his whole family to Jerusalem on such occasions. Other Israelite men likely did the same. God’s people today likewise gather three times each year for assemblies and conventions."
I don't remember reading any command from Paul saying we must assemble three times a year per the old Law covenant. With that in mind Christianity seems to be based off all of Paul's opinions for that matter.