I asked an expert, Jeff Nyquist. He responded indirectly, with an excursion through the continuum. This is what the history of communist united fronts, alliance, peaceful coexistence, detente, glastnost, and "dissolution" tells us. 

At first you cannot talk to the communist, because his goal is to destroy you. 

But eventually you talk to him, and find yourself shaking his hand. He is a human being, after all. He is charming. Why were you ever afraid? 

You then forget that he is a communist. And you forget what communism signifies. So you decide to make deals with him. You even say that he is not really a communist. And he nods his head. 

Nearly everyone is happy about the deals you make and the resulting promises of peace. You are praised by everyone. It feels so good. 

Then you discover the communists are cheating you in various ways. Every agreement you signed was broken before the ink could dry. But you can say nothing because you will look like an idiot for trusting in criminals and murderers. Everyone who praised these deals and supported you must also remain silent, for nobody wants to appear foolish. 

The years pass by and your country grows weaker in relation to the communist power. You are sufficiently self-deceived that you fail to realize enemy agents are inside your own government. You also fail to notice they are at work inside allied governments. 

These agents promote each other, and destroy the careers of honest public servants. Anyone who is corrupt or weak falls in line with them.  

Of course, all this happened because you shook the murderer’s hand. You sat down with a criminal and compromised yourself. You committed a wicked act and called it “good.” 

And posterity will curse you.