To a mother, it is a very real being.
I have seen men as deeply in love as you are, with women as liberal-minded as Rosalie, become very unhappy after marriage through the opposite ideas of the wife regarding the education of children.
You must remember how much more closely a mother's life is entwined about her children, and how much more of their association usually falls to her than to the father.
This is especially true of daughters, and is true of sons up to a certain age.
You can understand, I am sure, how much more companionship a mother would find in children who accepted her faith and attended her church than in those whose spiritual paths led in another direction.
I know Rosalie realizes that a good life, not a certain creed, leads to the goal she seeks, after this phase of existence closes, and she does not ask you to change your faith. But while she would also believe her children were on the road to that goal, she would want them to walk through her path and by her side.
It will be hard to relinquish the woman you love, to-day, for the children who might not come to-morrow.
Yet I can give you the counsel you asked on this matter only from my personal observation of similar unions.
I should advise you to try an absence of some duration, and to forget Rosalie if you can, since you have not yet declared yourself.
Better a little temporary sorrow than a life of discord.