The Catholic Education Service also says it's "absolutely essential" to include parents in how sex and relationship education (SRE) is formulated, delivered and evaluated, and whilst their schools would teach SRE from a Catholic perspective, they would "explore" and "respectfully listen" to those who disagree.
Its comments came after the Education Select Committee released a report calling for SRE to be made compulsory for all state primary and secondary school children in England.
However campaigners have criticised this recommendation, saying that primary school children aged 4 or 5 are too young for education on these issues.
Phillip Robinson, from the Catholic Education Service, told Premier: "It's essential because we need to help them to live with integrity.
"In a world where their values are under threat from the media, from society in general... we need to help them to navigate the world in a way that allows them to live according to their values and in a way that protects them...
"You have to do the relationships and sex education in an age-appropriate way, and I can't imagine any context in which it would be age-appropriate to teach four and five-year-olds about sex, but you would be teaching them about relationships and friendships, to protect themselves from bullying and exploitative relationships.
"There's a Catholic ethos in Catholic schools and that's where we begin. Of course that doesn't mean that we don't acknowledge and recognise that other people disagree with us, and we would even explore that disagreement... but we'd always be really clear about where we stand and respectfully listen to those who disagree."
Listen to Phillip Robinson speaking to Premier's Aaron James: