I think of the words from the Christmas carol, O Holy Night:
"Long lay the world in sin and error pining
Till he appeared and the soul felt its worth."
The shortest days of the year--and the longest nights--are in late December. I've always enjoyed the timing of celebrating the birth of Christ (whether truly born at this time or not) during the bleakest, darkest period of the year. To celebrate Jesus' birth in the middle of winter, when the world is coldest, darkest, and the most dreary to me is a really fitting time. (Yet I know lots of places are sunny all year, and of course the land down under is enjoying summer... I think if I lived there, I'd want to celebrate Christmas during the coldest time, if it were ever possible.) We have a lot of reason to be happy and cheerful--the weather just sharpens our appreciation of it.
Do you refuse to use wine (pagan god Bacchus promoted it) or wood (the stake/cross was made of wood and used by Romans) or whatever else the 'pagans' may have used, just because they used it and 'tainted' it? God created nature--the earth and the heavens, the trees and the stars. They are all good. They are all still His-- and imo even more so now as God redeemed everything out of all the types of ways creation may have been misused/misunderstood/worshiped thru the centuries. Stars are not worshiped at Christmas, but have an honorable role in pointing to Christ. Evergreen trees endure the awful coldness and make us smile with their green life and fragrance, and point us up toward the heavens (unless you have a Charlie Brown tree!).
There's a lot of beautiful symbolism that you can begin to see and appreciate. Winter time brings many of the understandings of Christ's birth to be more sharply seen and appreciated. That's why I have no problem with it at all. God redeemed people... but I think He also redeemed nature for us as well. It's okay to use it, or maybe you can see other symbolism available where you live that reflects what Christmas presents.
All imho.
bebu
Edited to add: Christmas presents are a great tradition! "It's better to give than receive"... so if someone is giving you a gift, they are doing something that God blesses. Why refuse them their opportunity? ...The wise men brought gifts on Christmas; did Mary and Joseph refuse gifts from "pagans"? Nope. ...Lastly, Christians celebrate the gift of God to humanity at Christmas time--God's giving us "worth", like that carol above goes. Whether other gifts are exchanged or not, it's fitting, imo, to gladly acknowledge that one Gift, if nothing else...