I’m still trying to figure out the connection between donating/not donating blood and Christianity.
There are only two particular denominations that have prohibitions against blood either giving or receiving.
If you are not a member of either of those groups (and you have given no indication that you are) you might as well ask if it’s ok to be an atheist and donate blood.
Both questions are equally illogical. One has nothing to do with the other. Mainstream (majority) Christianity has no policy on the matter and afaik neither does atheism.
It’s an illogical question which doesn’t really have a clear cut answer because there is no policy covering it. Mainstream Christianity is silent upon the matter so how could there be a definitive answer?