The campaign for the Democratic nomination for the U.S. Senate from Virginia, a campaign in which religion is suddenly playing an important role, will reach a crucial point at noon today when thousands of party members gather at "mass meetings" in every city and county to choose delegates to the June 9-10 nominating convention.

Party officials said yesterday that none of the eight candidates is likely to emerge from the local meetings with a commanding lead. Although former state attorney general Andrew P. Miller and State Sen. Clive L. DuVal II of Fairfax County are generally considered to be the front runners, when the votes are tallied today neither is expected to be within easy reach of the 1,398 votes needed to win the nomination.

Because of the close race, increasing attention has been focused during the past week on G. Conoly Phillips, a Norfolk City Council member and car dealer who is a born-again Christian running his senate campaign as a "ministry unto the Lord."

Conoly Phillips has been conspicuously successful in the last weeks of the campaign in inspiring Christian supporters to prefile as delegates committed to his candidacy. Many campaign officials now believe that he may come out of the mass meetings with 200 or more delegates pledged to vote for him in the nominating convention at Williamburg.

Few Virginians expect him to be the nominee, but many believe that his delegates will vote as he directs at the convention and will possibly be in a position to put Miller, DuVal or one of the other candidates over a majority count after the first ballot.

Other candidates in the race are former state delegate Carrington Williams of Fairfax County, former Fairfax supervisor Rufus Phillips, state Sen. Hunter B. Andrews of Hampton, former chairman of the Fairfax supervisors Fred Babson, and Flora Crater, a Falls Church feminist and 1973 independent candidate for lieutenant governor.

Today's meetings are open to any registered voter who will promise to support the Democratic nominee in the general election next Nov. 7.

The delegate selection process is fairly simple. Those attending the meetings will be given a chance to assemble into caucuses, supporting one of the candidates or in another caucus favoring uncommitted delegates.

If any caucus numbers less than 20 percent of those attending the entire mass meeting, its members will be given one chance to join the caucus of another candidate or the uncommitted caucus, if it numbers more than 20 percent of the total.

Then each caucus will be alloted a percentage of the city or county delegates in proportion to its representation at the meeting. For example, if half of those at a meeting join the uncommitted caucus, half of the delegates chosen will be uncommitted.

Each caucus will be allowed to elect its delegates from a list of those who prefiled. If no one prefiled or if a caucus is entitled to more than the prefiled number of delegates, then additional delegates can be nominated and elected at the meeting.

Committed delegates will be bound to vote for the candidate of their choice for only one ballot at the state convention. After the first ballot, they will be free to vote for any other candidate.