"God loves everyone unconditionally." I hear this a lot - but I don't see any justification for this in scripture. 

To be clear, there is a sense in which God shows his love to all creation. He sends his rain on the just and unjust alike! (Matthew 5:45). The wicked enjoy all the benefits of his creation just as much as the righteous. So in that sense, yes, this kind of love is definitely without conditions..... however....

Old Testament : Deutoronomy 28 - read it. The blessings to the nation of Israel were conditional upon obedience!

New Testament : John 3:16 - The most well known passage to all Christians. "For God so loved the world that he gave his only begotten Son, that whoseover believeth in Him, should not perish, but have everlasting life."  The invitation is Universal - whosoever. But the condition is right there... whosoever believeth in Him. Not everyone gets everlasting life! Otherwise it's clear... you perish!