Should winter solstice be a celebration for Christians? It seems to have originally been a celebration feast for pagans. Most pagan celebration feasts were times of sacrifices to gods and other spirits, which the original apostles commanded be avoided. They were times of sprinkling of blood of sacrifices onto the feast participants and then eating of the sacrificed meat by the participants in the name of the god or spirit. Once Christians converted to only worshipping the One True God, the Father, they were duty-bound to forsake such ceremonies, although for some it was very difficult to do so. This difficulty might be why Christmas was eventually celebrated at solstice time, to allow celebrations to coincide with pagan feasts to allow Christian converts to continue celebrating but with a Christian narrative instead of a pagan one. Hence pagan traditions got incorporated into Christmas - presumably to allow a compromise where feasts could continue under a different guise. But the original command to Christians is to forsake the things associated with sacrifices to such gods, regarding these gods as idols, and just to worship the Father as God. Now it could break up families and churches if a believer in Christ were to stop celebrating Christmas so I leave it for personal discretion. Personally I try to avoid such associations with pagan customs, in obedience to the command to cease from idol meat and blood. How far you go in this dissociation is a matter of conscience, but the general attitude of obedience to the command of the apostles is a matter of acceptance into church life. We cannot participate in worship of other gods and spirits once we turn to worshipping God the Father, it is not allowed. The Father is a jealous God.
Each one must think about how their obedience affects their family and associations, jobs, careers, lives. Those who give guidance must bear in mind that the consequences might be regulated and they be made answerable for the effects their advice has on others. Plus the apostles strongly rebuked teachers whose teaching destroyed families. So we should exercise an abundance of care. My own life and family has been greatly affected, negatively, by my obedience in things such as this and sabbaths too, so I know it can be very costly. Sometimes even deaths can result. So yes, glory to God when we endure hardships for His sake but be extra careful it truly is in the line of duty and not some badly worded advice or misunderstanding or falsity that led to the problem. For example, although we might avoid pagan traditions once associated with pagan feasts which Christian apostolic teaching calls idolatry, it is worth noting that the idolatry might be long gone and those traditions have no modern association with sacrifices to deities or spirits we call idols. It is hardly part of our lives today in highly Christianised countries and communities to come across sacrificial feasts to idol gods. So there is not the same need that there used to be to avoid the pagan traditions now that they are vestigial and harmless. It is not worth breaking up families over it, or losing a job over it. We have to judge it for ourselves in our own situations or those of the people we might advise. Discretion and individual conscience.
