to be clear: i don't have any particular aversion to rebirth celebrations. i'm maybe a little beyond it. but, if it makes you happy, whatever.

i'd just request that you take the time to actually understand what you're doing - and that means researching the history of this over comparative mythologies in order to understand the syncretic basis of it.

you shouldn't look at this as debunking something. rather, you should look at it as better understanding it. if you're getting all of your information from a specific tradition, whatever it is, you're blocking yourself off to the other perspectives.

the rebirth festival is easy enough to understand. it is close to the spring solstice, and meant to represent the end of darkness and beginning of light. i may argue that the astronomy of it is not a reduction but a complication, as it is fascinating on it's own basis. but, if you're so inclined, a better understanding of these themes is likely to deepen your experience, rather than negate it.

i will fully admit that i have an ulterior motive: encouraging people to seek naturalistic explanations of things will likely separate them from the more dangerous components of religious observance. but, i'm not being disingenuous. if you like these holidays, why not learn more about where they came from?