ap⋅ti⋅tude [ap-ti-tood, -tyood]
-noun 1. capability; ability; innate or acquired capacity for something; talent: She has a special aptitude for mathematics. 2. readiness or quickness in learning; intelligence: He was placed in honors classes because of his general aptitude. 3. the state or quality of being apt; special fitness.
No, it is not unmodifiable. You can change your religious preferences at anytime; especially how you worship, who you worship and where you worship.