How do I switch from luminous to apostle?

[trueido]

I am at the second quest of the Luminous Templar and I can't switch side for some reason..
I saw people said I should go talk to Septum Uru but he just says nothing about switching and there is no such an option..

[arcanefid]

I am at the second quest of the Luminous Templar and I can't switch side for some reason..
I saw people said I should go talk to Septum Uru but he just says nothing about switching and there is no such an option..

You should complete the whole questline before you can switch sides.