Claims that faith schools are cherry-picking the brightest and most wealthy pupils are to be rejected by the Archbishop of Canterbury.
Dr Williams will reject the claim that faith schools are divisive
Schools with a religious ethos help provide the "broadest possible access to ideas", Dr Rowan Williams will tell the National Church Schools conference.
He will say that church schools are often the main educational presence in some of the most deprived areas.
The National Secular Society said faith schools were "self-evidently divisive".
The archbishop's remarks follow claims that church primary schools in England are less likely to take in children from low income families than local authority schools.
A study from the Institute for Research in Integrated Strategies found schools in the voluntary-aided sector had fewer poorer children than was expected after judging their area's social make-up.
Dr Williams will say: "The often-forgotten fact that church schools are the main educational presence in some of our most deprived communities means that it simply can't be said that these schools somehow have a policy of sanitising or segregating."
The Church of England's chief education officer, Canon John Hall, told the BBC there was evidence to show that Church of England faith schools had similar proportions of children from deprived backgrounds as other schools.
Canon Hall said underprivileged children did "rather better" in faith schools, adding: "We are not socially segregated and we are not exclusive."
But Liberal Democrat MP Evan Harris accused faith schools of selecting children on the grounds of their parents' religion - a practice he said was wrong in today's society.
The MP, who is a member of the National Secular Society, said: "There's not a shred of evidence that being a faith school in and of itself improves results."
'Benefit to society'
Faith schools have been put in the spotlight by the government's Education and Inspections Bill in England. MPs will vote on the bill on Wednesday.
Under this, schools will be able to set up "trusts" with outside bodies, including faith groups, with more say over admissions and budgets.
Dr Williams will tell the conference in London that society would benefit from close partnerships formed between faith groups and public bodies.
Catholic and Church of England leaders have already backed changes to the bill which would outlaw the practice of interviewing parents.
In his speech Dr Williams will back national criteria for admissions to voluntary-aided church schools in an effort to make applying easier for parents to understand.
Interviewing is against the admissions code and few schools in England do it.
But a test case involving the Roman Catholic London Oratory School, where Tony Blair sent his sons, showed this could not be enforced.
Dr Williams will also call for faith schools to teach about other religions and explore the possibility of exchange visits between schools.
"Church schools are among the relatively few public institutions generally regarded with trust by minority religious communities," he says.
"And it is this... which gives the lie to any idea that faith schools are automatically nurseries of bigotry."
The archbishop's defence of faith schools was described by the National Secular Society as "disingenuous and self-serving".
Its executive director, Keith Porteous Wood, said: "The concept of faith schools is self-evidently divisive."
He added: "The whole point of faith schools is for them to bring youngsters to the one true denomination or faith.
"Implicitly, if not explicitly, those who do not follow the faith are regarded as inferior. Some preach that non-followers will face eternal damnation, torment and burning in hell. Nothing could be more divisive."
He added: "The one and only chance to teach integration is to children at schools which reflect the diversity of the whole community.
"We should make all state schools open equally to children of all faiths and none."