When I am playing as a viking and I want to convert to a new christian faith or a new muslim faith (to give them a viking approach and to use the new faith icons 
) I first have to convert to an existing christian or muslim faith and then create a new viking/christian or viking/muslim faith. So logically I take one step forward and then half a step back (towards the Vikings), which makes no sense.
So what I suggest is this:
When you convert to a religion from a different religious group (like for example from christian to muslim) you get the choice create a new faith inside that new religious group, maybe with some restrictions like higher conversion cost or that you have to keep 1 or 2 tenets from your old faith.
) I first have to convert to an existing christian or muslim faith and then create a new viking/christian or viking/muslim faith. So logically I take one step forward and then half a step back (towards the Vikings), which makes no sense.So what I suggest is this:
When you convert to a religion from a different religious group (like for example from christian to muslim) you get the choice create a new faith inside that new religious group, maybe with some restrictions like higher conversion cost or that you have to keep 1 or 2 tenets from your old faith.