In my walk, once I discovered the switch to Sunday and a few other doctrines were not biblical, I set about trying to find out where these things came from. As it turns out, Sunday, Christmas, Easter, and a bunch of other doctrines of mainstream Christianity come from pagan religions. These are direct practices of other religions that have been melded into Christianity. Did you know mixing the worship of other faiths into the faith of Yeshua is the most rebuked sin of the bible and the one that caused ancient Israel the most trouble?
These things matter. How we worship matters. It shows which God we are serving. As for me and my house, we serve Yahweh in the Name of His Son, Yeshua.