Is it the islam a religion very cruel becuase of their horrible punishments and intolerance?

I have read the Quran and other sources.. where Islam applies terrible punishments and most of them are similar to the Bible but christians and jewish people don't apply them anymore but islamic countries apply terrible punishments specially the shariah.then why does the Quran repeat Allah is merciful? if a thief is mutilated of this hand? what do muslims think about these punishments? are there liberal muslims or muslims who understood these punishments for the community of medinah or mecca or something like that? not for all the muslims