I don't have to. Ann Coulter already wrote a column defending him, and sourced a book that defends McCarthy, citing Kremlin records, at far greater length.
Even in the event that McCarthy made a few mis-steps or errors (there are no famous people that I agree with on all their actions) that doesn't change the fact that he was essentially correct about the level of communist infiltration in that era, and the Democrats' nation-threatening indifference to it. Period.