Expand signature We're all marching towards death, only the length of the journey differ - Spartacus. About nomads, the province they occupied instantly change to the Khagan religion IIRC, so it doesn't really count since it's different than tribal gov. Otherwise you can wait and hope that some good christian will send a missionary to you, but that can take. Make her your concubine, and then you should get a decision to change to her religion.
Probably the quickest way to change is raid down some holdings until you grab a female catholic prisoner. Not everyone likes warmongering, surprisingly. Crusader Kings 3 also includes a toggle labeled “same-sex relations.” This changes the game world’s view on homosexuality from the default - in which characters can be homosexual, but it.