The mother, called Anna, attacked the awareness week at King Solomon High School, in Redbridge, after her 16-year-old daughter arrived home with an 'LGBT Week' badge.
"You cannot force this filth on children. It is not lesbian, gay, bisexual and transgender week in my house," the mother wrote.
Anna, who has since removed the Facebook post, wrote that she was shocked children aged from 11 upwards were asked to wear the LGBT badge at school.
The school had devoted the week to activities that promote tolerance and understanding of gay, lesbian, bisexual and transgender issues, according to the Jewish Chronicle.
Students were provided with rainbow flag badges and asked to come into school in rainbow-coloured clothing on one day. Money was raised for the Terrence Higgins Trust, a HIV and sexual health charity.
Anna continued in the post: "We will be serving the Lord as usual and not promoting sin so KS High School, you can keep your abomination badge."
The post attracted outraged comments from other parents, according to the Jewish Chronicle. These can no longer be viewed now the post has been taken down.
Ruth Landsman, who has twin boys at King Solomon, wrote a Facebook post in response, saying: "If one child goes home from KS High School this week no longer considering taking their own life, job done.
"So pleased that the school has chosen to support LGBT week and promote tolerance and understanding in our community."
She later posted an update, after recieving a post from a complete stranger who had seen her supporting the LGBT week on Facebook.
The message to her read: "I am 20 years old and I came out to my family when I was 12 (I always knew I was gay), it was terribly painful, the worst thing I ever went through, the experience was so scary sometimes I cry when I remember it.
"Thank you so much for that beautiful comment of yours, it restored my faith in humanity and made me feel so much better. You are amazing and your children are soooo lucky to have you."
Deputy headteacher of King Solomon, Sam Walters said, according to the Metro: "We haven’t heard from the mother, but I have had parents writing to me to say how thankful they are and how their children have come home this week really interested in what they are learning.
"As a school, we have a duty to prepare our students for life in modern Britain."
Teacher Has Best Response To Homophobic Parents, After Pupils Are Pulled Out Of Class Because He's Gay