A pilgrim is simply a person who travels to a sacred place for religious reasons.
This definition is applicable to every single religion and sacred place in the world, such as Jerusalem, Varanasi, Mecca and Santiago de Compostela. Note that the above definition does not state how the pilgrim must travel. Indeed, the vast majority of pilgrims now fly or use some type of motor vehicle to reach their destinations. Santiago de Compostela is not an exception to the norm.
So, when you read that pilgrims had virtually stopped walking to Santiago in the 20th century, this is true. However, it does not mean that pilgrims stopped going to Santiago. Rather, it means that they had opted for other means of transport.
The extraordinary and exceptional case of the Camino de Santiago
Despite being a Catholic pilgrimage route, the Camino de Santiago is arguably the only pilgrimage route that welcomes absolutely everyone, no matter what faith (if any) they profess. Furthermore, Catholics do not receive any benefits or extras along the Camino. There is literally not a single place or event that is barred to non-Catholics. Catholics may, however, partake in rituals particular to their faith.
People who travel to sacred places, and do not do it for religious reasons, are considered tourists. However, this is not the case of the Camino de Santiago. If you have decided to walk to Santiago de Compostela, you become a pilgrim. At least that is how the local Spaniards will see you.
And remember, the Camino de Santiago is one of the very few pilgrimage routes that is set up for walkers and hikers thanks to its well-marked trails and pilgrim services. Are you ready?