Most of holidays we celebrate today are not mentioned in the Bible because it's an ancient book. However the Bible does give us some guidance.
God's son taught us about our heavenly Father. According to Jesus 'the law' or correct doctrines are not as important as the love his followers would have for their 'neighbors' (not just fellow believers).
Preoccupation with the law, correct doctrines, selff-righteousness, and hypocrisy was the realm of the Pharisees. Jesus warned against the leaven of the Pharisees. Luke 12:1; Matthew 16:6; Matthew 12:11
Jehovah's Witnesses are not allowed to question the wisdom of their religious leaders. Everything they say is thought to be 'the truth'. Disagreement is not welcome. In fact, asking too many questions can lead to apostasy, disfellowshipping, disassociation, and shunning.
Jehovah's Witnesses are trained to avoid independent thinking. 'How is such independent thinking manifested? A common way is by questioning the counsel that is provided by God's visible organization.' Watchtower Jan 15, 1983 page 22
Let's pray that some day soon, Jehovah's Witnesses will be free to worship God according to their conscience and without fear. 1 Timothy 2:5; Galations 2:21; Romans 10:4 1 John 3:23; John 6:67-69