Explanation:
Two days ago, I biked my first outdoor imperial century (AKA over 100 miles), but didn’t immediately take a picture of my watch displaying the data as I usually do.
Today, I tried to access it and found out that the watch deletes all data weekly and considers Sunday the first day of the week.
What it has to do with Christianity:
It makes absolutely no sense to consider Sunday the first day of the week rather than Monday. Unless you follow stupid standards established by people who consider the last day of the weekEND holy and thus want to give it pride of place as the starting day rather than the final day of the week.
Then I fear blaming Christianity is a bit weak. I get that you are annoyed. I might be too if I could be convinced to exercise. I think you are hitting this annoyance nail with too big a hammer. Because the fact that a week consists of seven days is also due to the influence of Christianity. And even in sensible the-week-starts-on-Monday-Europe wall calendars on sale often list Sundays first. Your mobile phone probably has a setting for that as well. Take it as a lesson learned and let it go.