You're the hero. You're the Messiah. So why don't we have peace?"

That cruel taunt was hurled at Prime Minister Menahem Begin during a bitter parliamentary debate the other day. It expresses the not uncommon view that Begin is a great showman but too much of a religious hardliner to make good use of the opening for peace created by the visit of Egyptian President Anwar Sadat.

Because of the euphoria surrounding the visit, I tried to reflect the skeptical view when I interviewed Begin the other day. I put to him as many specific questions about negotiations as I could.

Our talk took place in his Jerusalem office. He bounced up from his chair, greeted me warmly, and began talking at a clip that dispelled any thought of physical frailty lingering from his recent heart attack. He referred laughingly to the bitter parliamentary debate.

"In the Knesset," he said, "I'm in my element. I love the give and take. It can be done with humor and without rancor. Everybody talks to everybody in the Knesset. In the Knesset even my wife talks to me."

I asked him how the Sadat visit had changed his ideas of making peace. "Not in any way," he replied. "I always said for 29 years that there should be direct contacts between us and the Arab leaders. So I think his coming here was normal. We are ready for any other Arab leader to come as President Sadat did. I would particularly like to meet President Assad of Syria. President Carter told me he was a most impressive man."

I asked Begin if he is driving toward a separate peace with Egypt. He said: "We don't want to drive wedges between the Arab states. We deliberately avoided any suggestion of that when Mr. Sadat was here. That's one of the reasons I haven't gone to Cairo. Some people call it tactics. I call it tact. Sadat needs to be able to face Jordan, Lebanon, Syria and the Palestine Arabs, and say that he has put their case to the Israelis in the strongest way. That gives him moral strength."

I asked him whether, to bring into the negotiations King Hussein of Jordan and the Palestinian Arabs, he was prepared to make concessions on the land on the West Bank of the Jordan River, which was seized by Israel from Hussein in 1967.

"You are not supposed to start negotiations with concessions. You start with differences of opinion and you narrow them down. Sadat and I know what our differences are, and we are prepared to negotiate an accord. The bargaining is at a delicate stage, so I cannot say more now."

I said he must have in the back of his head some idea of where he wanted the negotiations to come out. "Not in the back of the head," he interrupted. "In the front of the head. How to make peace is first among all our thoughts."

In an effort to pin him down on the West Bank where Israel now rules over 700,000 Arabs. I asked if he would prefer to have those Arabs inside Israel or have a border that was unsatisfactory from a security point of view. He said: "Many countries use the term 'security' to cloak aggressive intentions. Not us. By security we mean that our civilians won't be killed. In Nahariaya near the border in Lebanon last month a rocket came out of the sky and killed a woman. That left two children without a mother. We do not want to have any more Nahariayas. That is our concept of security."

That didn't sound like the language of concessions, so I asked if he wasn't afraid negotiations would drift into a separate peace with Egypt. He said: "Don't use terms like drift. That is a negative expression. In the Middle East there are deserts, and the sands are moving. We shall keep seeing each other. We shall see that there is no more war, we shall have peace."

I asked Begin about his concept of leadership. He cited "the tradition of the maccabees. It is a tradition of fighting with heroism and seeking allies. Everybody knows about Massada where the Jews, instead of yielding, let themselves be massacred by the Romans. That was heroism associated with downfall.

"I am talking of heroism and victory. That means looking for allies."

Begin then cited his warm relations with Carter, Sadat, President Nicolae Ceaucescu of Rumania and Prime Minister James Callaghan of Britain. He said: "We must avoid the curse of Balaam in the Bible. We must not be a people that walks alone and is not counted among the nations."

I came away knowing that most of my questions had been finessed. But deeply impressed, even exhilarated. I asked one of Begin's aides for an explanation.

He said: "Begin took office at the age of 64 after 30 years as a polemicist in the opposition. He can't resist rhetoric and debating points. But he is the only remaining leader who has lived the Israeli saga from the Holocaust through the fight against the British and the wars against the Arabs. He is the last of the last. He has history in his veins."