Locke,
Like I said above I don't think it is a crime in Singapore to proselytise and spread one's faith whatever it may be, apart from the proscribed ones.
Let's say a Christian approaches a Muslim along the street and asks the Muslim if he wants to listen to a short take on Christianity. Would this act in and of itself be characterised as a crime? On the face of it I would think not.
The critical issue appers to hinge on the method and mode in which it was done. And it is in this regard that Dorothy and husband appear to fall foul of the law and thus their acts being characterised as seditious.
Cheers