Sagrada Familia stained glasses
Stained glasses was common in European Catholic churches. And Sagrada Familia had lots of stained glasses too.
And with Gaudi, of course it would be different.
Spanish sun is amazing. Sunlight is strong and hard. Gaudi probably had a precise calculation on sun. Every stained glass in Sagrada Familia was set up to get the strongest sunlight. It was a strong sun outside but it was a soft colorful light in the church through the stained glasses. The soft colorful light surrounded the people in the church gently.
Even a villain was covering with a layer of holy light when he/she walked under the soft colorful light. Heaven could be glimpsed in this beautiful light.
I could imagine Gaudi believed in all the goodness. Everyone is an angel in his eyes.