To create material wealth, there is no method more efficient than capitalism. But by its very nature, capitalism distributes its beneficence unequally -- widening the gap between rich and poor.

The democratic process corrects the excesses of capitalism by narrowing that explosive gap. Take, for example, the struggle over "lifeline" banking.

Deregulation has created a wide range of high-interest, low-fee bank accounts for people with money. But it is rapidly cutting low-income people out of the system.

Children can't find banks that offer starter savings accounts. Some banks refuse checking accounts to low-income working people. Some who do keep accounts have to pay stiff fees for their low balances.

The elderly who are dependent on Social Security find they can't even cash a government check at many banks. Instead, they're forced to use check-cashing services, where they may even be hit by thieves on the way out the door.

Bank branches are closing in many low-income neighborhoods, leaving residents and small businesses without local banking services entirely. The banks say, "That's capitalism." Now that they're paying market interest rates on savings, they can no longer afford to offer free services to holders of small accounts.

But legislative activity is taking shape in 12 states and at the federal level to prevent the banks from turning their backs on lower-income customers.

The goals of the "lifeline" movement are best defined by a bill introduced by Rep. Charles Schumer (D-N.Y.). Among its provisions:

*The customers of all financial institutions would have to be offered basic checking accounts, with no minimum balance and no fees or maintenance charges. They could open these accounts with deposits as low as $25.

*Basic checking accounts could be sharply limited, so as to appeal only to people with small incomes. For example, customers could write only eight free checks every month, paying $1 per check thereafter.

*Fees for services such as stopping a check would be held to a minimum.

*Any consumer could buy an inexpensive check-cashing card, allowing him or her to cash government checks (for example, Social Security checks) without further charge.

*Institutions would not be allowed to expand across state lines unless they kept their doors open to low- and moderate-income customers.

No state has passed a lifeline-banking law, although several appear to be close. In Massachusetts, state-chartered institutions have to offer no-fee checking and savings accounts to customers under 18 and over 65, but that's not the same thing. Most older people are not poor and can afford today's higher banking charges. The social need is to address lower-income customers of all ages, and assure their access to the financial system.

Naturally, the banking institutions object strongly to any law that would require them to serve the poor. But the sharper bankers among them see this as an issue that won't go away. The American Bankers Association has been encouraging members to develop their own economy checking programs voluntarily. ABA spokesman Kirk Willison told my associate, Virginia Wilson, that about 45 percent of the largest banks either offer no-frills accounts, or plan to.

The Riggs National Bank in the District just began an account that approximately follows the Schumer guidelines. In California, Security Pacific and Bank of America offer competing discount or self-service accounts; and Sears' S&L offers free checking to customers willing to forgo copies of their checks.

But a spokesman for Rep. Schumer said that these are only "highly publicized examples" rather than a trend. Many no-frills accounts require customers to use teller machines rather than visit human tellers. This often is troubling to the elderly.

Alan Fox of the Consumer Federation of America says that voluntary action by some bankers won't stop the drive for lifeline laws. And next year, the lifeline issue may heat up even further.

Starting in 1986, interest-rate ceilings will be removed from small savings accounts (now paying a maximum of 5.5 percent). Some banks may start phasing out passbook accounts for small savers then. If that happens, lower-income people would be denied a secure way of paying bills and a secure place to keep their money.

Basic banking services are a necessity of modern life. Every industry has some sort of social obligation to the nation that nurtures it. For the banking industry, that means lifeline accounts.