Purified or Punished?

As the people of Israel waited for the coming of their Savior in the time of the prophet Malachi, there was much hope placed in what this Savior would be and what he would do for God's people. Many people view Jesus' return in the same light... but sometimes we forget that his second coming will also be a time of judgement for all the people on the earth. So how do we know if his judgement will purify us...or punish us?