Before discussing the killing and choking of chemical warfare, Theodore Gold, the Reagan administration's chief promoter and explainer of nerve gas, offers cookies to a visitor. In Gold's Pentagon office, which is secured by a combination- lock door, the work of defending America against aggressors also includes cookies as a deterrent force against sneak attacks of the mid-afternoon hungries. Wherever the war, the Pentagon mounts a united front.

Gold, who is an athletically trim 43 and an engineer who has worked in the research and development of nuclear weapons at a Livermore, Calif., laboratory, has been the deputy assistant to the secretary of defense for "chemical matters" for 16 months. He has been busy of late, with Congress about to decide whether to lift the 14-year freeze on production of nerve gas.

As the human face and breathing body behind the Pentagon's managerial texts that speak of chemical warfare policy, Gold appears at first to be miscast. He has a companionable, I'm-just-a-regular-guy manner, and he talks of his "special abhorrence" of chemical wespons. He has been consistent. In May 1982 he said that "if ranking weapons on their immorality, nerve gas would be at the top of the list."

These are the required protests, as standardized in Pentagon lingo as rifle salutes at a general's funeral. After these proper anti-barbaric references, it was Gold's time for fun: cool-headed distinction-making. Imperturbable, he is good at distancing himself from what he calls "the smoke and noise" of the debate.

He welcomes the challenge of confronting opponents of nerve gas like Sens. David Pryor (D-Ark.) and Mark Hatfield (R-Ore.) who argue on moral, economic and tactical grounds against removing the nerve-gas ban. The Pentagon, says Gold, should pass muster on the obligation to be clear-headed in making its case: "We're now saying that we want to resume production after a freeze, or whatever you want to call it, and the burden should be on us to say what has changed and why we want to produce it."

The changes on Gold's mind are those of the 1970s, when, with the United States out of the nerve gas race, the Soviet Union roared ahead. Now, according to Pentagon claims, its chemical arsenal is large and its troops well-trained in using it. The only purpose in getting back to even, says Gold, "is to deter the other side. The only way we know how to deter is to have a strong protective posture and also the ability to retaliate if he uses them first. That would put him into a protective posture and then he would see no advantage in using them."

Gold has been trying to persuade Congress that the current stockpile is not adequate. He is not shy about telling his dovish opponents that they, not he, are the graver threats to peace. Gold told a House subcommittee in April that if our current stockpile is inadequate "then failure to redress this situation makes war more likely, makes escalation to more terrible forms of war more likely, and makes arms control less likely."

Gold gives shorter shrift to an April 1983 report from the General Accounting Office that criticized the Defense Department's poor case for pushing ahead with chemical war preparations. The claims made for modernizing nerve gas weaponry, said the GAO, "are not supported by empirical evidence and must be recognized as possibly inaccurate."

Gold dismissed the report as shallow, worthy of an F if he were a teacher grading it. For many in Congress, the GAO's investigation earned an A-plus. It persuaded them that the Pentagon should be denied money for nerve gas. The House had a 14-vote margin against production and the Senate tied 49-49, with Vice President George Bush, pro- nerve gas, breaking the tie.

In the end, Gold, though quick of mind and a relisher of debate, couldn't do much more than rely on the deadweight phrases found in the Pentagon's promo sheets for its other weapons: the Soviets have superiority; we need deterrence; we need a bargaining chip; we must send our enemies the right signal.

Gold's thinking was on the mind of Pryor, the leading critic of nerve gas, during the Senate debate. Pryor said: "on weapon after weapon, cause after cause, this seems to be the mentality of this city, of this town, of this administration, of this Congress, of all of us -- let us build more, let us produce more, so that ultimately we can have less."

Gold didn't have a high regard for Pryor as an intellectual opponent. Apparently, the Arkansas senator lets his emotions enter the debate. He can't distance himself. He's unmanagerial.