It’s a heck of a rabbit hole; and way more to unpack than many folks can.
Simple advice, “Paul encouraged folks to let folks work out their faith.” What you believe, and how you live it is part (first) of a collective faith, then of your individual steps in that faith. If you will. You will pick up and pit down many things. It’s ok. It’s encouraged.
For the holidays you choose to celebrate, be open to others’ views but convinced of your own. Christmas, Easter, and several others have been co-opted by many secular and non-secular folks over the ages. Passover and Ramadan seem to have been better able to keep a separate (holy?) framing in the greater view, though there’s arguments within on what is and isn’t good enough.
Be gentile with yourself as you take these steps. And give grace to folks who aren’t seeing things as you do. From there, follow the Creator and strive toward holiness. That’s going to help whatever holidays you celebrate resonate in truth for others