A new sex education resource for Catholic primary schools describes sex as a gift from God, which belongs in a committed relationship.
In an introductory note to the 'Flourish' programme, it also states that the Catholic Church's teaching in relation to marriage between a man and a woman cannot be omitted.
It was written by a former principal and developed by the Irish Bishops' Conference, which it says is "bright, fun, engaging, interesting and pedagogically sound".
The programme is for junior infant pupils up to sixth class and covers topics such as friendship, family, bullying, love, and personal safety.
In a statement, the Bishops' Conference said all teaching in Catholic primary school in areas relating to the church's teaching is done in an entirely invitational way.
It said that church teaching on a range of perspectives on relationships can be offered to pupils but obviously other perspectives will also be shared.
The introductory note to the resource also says the programme must not promote shame and goes on to say that puberty too is a gift from God.
The conference also said that the Constitution and the Education Act allows for the withdrawal by parents of their children from any aspect of the curriculum at both primary and post-primary level.
The Department of Education has said that access to sexual and health education is an important right for students and said it is important to note that the ethos of the school should never preclude learners from acquiring the knowledge about the issues, but ethos may influence how that content is treated.
In a statement it said the Government has committed to developing an inclusive and age appropriate curricula for relationships and sexuality education and that the National Council for Curriculum and Assessment is continuing its work on that.