Christ wasn't around during the great flood. So, no such thing as a "Christian God".
The great flood was a work of nature. Nature is cruel - but humanity can rise above it. Human Rights will show the way.
As for going to Church whilst menstruating (not a problem for you since you are 62, unless you take HRT) - you can go if you do not feel too ill. But the Church would not force you to go or make you feel guilty if you could not go - so there is a "get-out-clause" for women who may be feeling weak since there is a lot of standing around.
Any more questions since you are clearly not familiar with the Greek way of life?