is playing guitar without a pick bad for your fingers?

I started learning using a pick, but I play bare fingers now and switching to a pick even for a minute throws me all off and I can't play. I never really cut my fingers, but it does hurt, especially when I switch between my Spanish guitar and my steel stringed acoustic. My fingers have grown too used to the nylon strings and pushing down on them more lightly so when I switch, it's almost as if my fingers are being hypersensitive.

No. My thumb has never been cut from many years of guitar playing. Either he is plucking or strumming too hard with his thumb or he need to change his strings. Rusty old strings are more rough on the hands. As for the fretting hand, after about a week or two, your finger tips start developing calloses that shield it from friction against the string.

If you play a lot of guitar you will find that it is your left hand that gets all of the real blisters. Playing with a pick has its advantages since you can articulate individual strings better but playing with your bare fingers can also be fun and gives the notes a softer sound which is good for mellow-sounding songs.

I wouldn't say it's bad for your fingers, but I would imagine that your fingers may become sore/callused/bleeding if you play for long periods of time. Playing any string insrument as such can cause that. I've been playing the violin for eight years now, and I've never had issues playing en pizzicato (plucking the strings with index finger or thumb), unless I either played for a very long time or plucked the strings really hard (this makes Bartok Pizz. very hard). So I would imagine that the issue is a long period of playing, or plucking too hard, but maybe that's because the violin's strings are smaller compared to the guitar.