Of course those two verses would not be in Sliabh na mBan, which is quite clearly a United Irishman song, an organisation which opposed any conflicts between different religious affiliations and called for the unity of "Catholic, Protestant and Dissenter" (i.e Catholic, Anglican and Non-episcopalian Protestant sects but didn't mention atheists!).

It is generally thought to have been composed by Mícheál Óg Ó Longáin, a United Irishman who it is believed participated in the Rising and had to go on the run afterwards, one of the few Irish-language poets or song composers dealing withe the United irish at the time, a movement the leadership of which was mostly of colonist background with English as their primary language. In addition, revolutionary Republican ideas were coming in from France, England, Scotland and the US, so that most of those too were in English.