Parents in Scotland should be allowed to choose how, when and whether their children learn about gay marriage in school, MSPs have heard.
Campaigners are calling for a change in the law to give parents a legal opt out from such lessons.
They say it would help avoid legal clashes between schools and parents over the controversial issue.
Rejecting an opt-out sends the signal that schools will teach about gay marriage “whether you like it or not”, the campaigners added.
The Equal Opportunities Committee at the Scottish Parliament is looking at the same-sex marriage Bill.
The call for a parental opt-out came in written evidence supplied to the Committee by Scotland for Marriage.
The group says parents have a right to have their children educated in accordance with their religious beliefs.
A Scotland for Marriage spokesman said: “School classrooms should not become a battle ground in the culture wars over the meaning of marriage, yet that’s what will happen if this Bill goes through without sensible safeguards.
“There are many parents of good will in Scotland who have concerns about gay marriage, and their beliefs deserve to be respected by schools.
“Any school that ignores the wishes of parents on this issue could find themselves breaking human rights laws.
“Parents have the right to have their children educated in accordance with their beliefs, and breaches of that right could end up in court.
“To avoid those sort of clashes, we think it would be wise to include a parental opt out for lessons on gay marriage.
“Parents already have opt-outs on sex education and religious observance, this would be an extension of that broadminded principle.
“Resisting such an-opt out speaks volumes. It sends the signal to Scottish parents that schools are going to teach gay marriage to your children whether you like it or not.”
Green MSP Patrick Harvie snubbed the idea of giving parents a choice. He said it “effectively calls for wide ranging discrimination in public services.”
The Scottish Government said: “We would expect any teacher or parent who has concerns to raise this with the school or local authority.”