The event was organised by the Ahmadiyya Muslim Community in Slough and took place at Burnham Park Academy on Saturday.
About 250 people attended to listen to talks on the theme ‘united against extremism’.
For the second year running pupils from Burnham Park Academy were involved, with ambassadors welcoming guests.
Art work by pupils from the school was also on display at the event.
Atiq Bhatti, president of the Ahmadiyya Muslim Community in Slough, said having a mix of speakers and guests was ‘very important’ for the symposium to be a success.
For the first time, the Royal Air Force and Windsor-based Household Cavalry were represented.
Also represented were Slough, Windsor and Maidenhead Churches Together, Thames Valley Police and the Royal British Legion.
Atiq said: “The symposium was to promote love for all and hatred to none.
“We are all brothers and sisters at the end of the day, regardless of religion or race.
“It is about service to humanity, about coming together and serving with one incredible voice that we are united against extremism.
“The guests that come every year said it was the best yet and our new guests said it was a nice event showing solidarity and unity.”