This is all both entertaining and somewhat fascinating but ...
Spiritual vs religious is a modern concept and it comes from the cult of the ego and public education that relies only on the literal and historical rather than including the experiential.
What it really means is being the same as a member of a religion but without subscribing to any doctrine.
Spiritual simple means being concerned with the human spirit or soul as opposed to material or physical things .... but think about that - if there is no 'other' which religious name God, then this a purely random physical manifest universe that carries on purely through cause and effect ... but .. if there is no 'other' then there is no reality outside of the material .. therefore no spirit, no soul, and also no quest.... to go further, to take that 'Other' (however you may think of it) out of the equation also means that there is no good and evil, no morality, no ethics ...
it also means that there can be no sacred spaces, opposed to profane, there is only this random universe with no meaning .....
So, you can do a secular Camino but you cannot do a secular pilgrimage - obvious really - Buen Camino