Hundreds of people opposed to the Government's plans to make incitement to religious hatred illegal, gathered in London's Hyde Park on Saturday.
The event was organised by the Evangelical Alliance but other Christian and non-Christian organisations have been taking part.
They say the plans, which are part of anti-terror legislation, will stifle free speech.
But ministers say it would not affect debates or jokes about faiths.
Another protest organised by the alliance will be held in Parliament Square on Monday.
About 300 people attended Saturday's rally.