Adulterers, cohabiting unmarried couples and those who kiss in public could all become criminals if a new Indonesian penal code is approved.
The draft reportedly proposes harsh fines and prison terms for those who flout the rules - drawn up to replace those inherited from Dutch rule.
Many say the existing code is flawed and outdated, but some activists are deeply unhappy with the new proposals.
But they would bring Indonesia into line with many other Muslim states.
Indonesia has the world's largest Muslim population.
Under the proposed draft, offenders caught kissing in the open could be jailed for up to 10 years and fined as much as 300 million rupiah ($33,000), reports the Jakarta Post.
Unmarried couples living together could be penalised with up to two years in jail and a maximum fine of 30 million rupiah.
It would also give police and officials the power to raid houses of all those they suspected of living together.
Justice ministry official Abdul Gani Abdullah said the law would only apply if others complained.
"Kissing in public is a crime if the people around are not happy and lodge a complaint. But if they think it's all right, then no action will be taken," he told the AFP news agency.
"The same goes with cohabitation. If neighbours think the presence of an unmarried couple living together is a nuisance, they can report to police."
Law expert and women's rights activist Nursyahbani Katjasungkana told the Jakarta Post the morality articles were excessive and infringed on the "rights of the body".
Legal expert Andi Hamzah asked: "What about tourists? Will we hunt them down too?"
The code is expected to be debated over a two-year period.