Bats are rated number 6 of the worst pets you could have. Too wild and they can carry Zoonotic disease amongst other things. Highly doubt that would be a good idea.
Bats sleep all day and fly around all night looking for food. What in their lifestyle makes you think they would be a good pet? If you are interested in bats, put a bat box in your backyard and watch them come out at sunset to feed. You get to sort of keep a bat and they will help keep your mosquito problem in check.
It would be safe for you, but probably not the bat. You're just as likely to get sick from your dog, cat, hamster, etc., and just as likely to get sick from a wild bat living outside. (They breathe too!)
Few people are actually able to care for bats, and lots of bat species are protected. Their long lifespans of several years are reduced to one or less, and they wouldn't be happy in a small cage and they'd also be extremely difficult to handle if it was a common little brown bat. (The big brown bat is a reasonable size, but lots of them are smaller than mice.)
Most people's arguments are that they'd be unhappy being anywhere but in the wild, but I find that to be a fallacy. Animals are happy as long as they get proper exercise, good nutrition, and are able to carry out most of their important instincts. (For example, cats "hunting" dangled string.)
If you're seriously considering getting a bat, you should research quite a lot and be prepared to pay a ton of money and time for permits and such. You might also become an animal rehabilitator, you might work with bats.
Is it safe for who? Bats are wild animals, and shouldn't be caged up ... Period. What kind of life could you possibly offer one?
It's not safe. Bats are wild and are not meant for tame domestication.