The Belgian Constitution holds an obligation for governmental schools to organise RE in the recognised religions and in non-confessional ethics for all children of school age. While neither the Flemish nor the French Community legislator can thus abandon RE altogether, both legislators have recently taken initiatives, moving beyond the opt-out system, towards an opt-in system and a partial withdrawal of RE in governmental schools. After a brief description of the Belgian RE system and its historical roots, we scrutinise these evolutions. Although the Constitution does offer some room for manoeuvring, not everything goes: ending the possibility for students in governmental schools to opt for RE in any of the recognised religions or in non-denominational ethics altogether would, for instance, not be allowed. This is different from the perspective of human rights instruments such as the ECtHR, which permits, but does not require governmental schools to organise moral or religious education. Following the margin of appreciation doctrine of the ECtHR, the ECHR does not pose strict limits on governmental possibilities. It remains, however, to be seen whether the Flemish and French Community will manage to stay in line with the stricter regime of the Belgian Constitution.