The present paper seeks to evaluate the seismic performance of the San Sebastian church and its vulnerability to seismic events. This colonial temple dates back to the 16th century and is located in Cusco, Perú. The church stands out for being one of the first five Andean temples erected in the city of Cusco and also for being one of the most outstanding expressions of baroque art. Due to its artistic and cultural value, this church was declared National Cultural Heritage in 1972. Unfortunately, the periodic occurrence of seismic events and a fateful fire occurred in 2016 have endangered the survival of the structure and the safety of visitors. Aiming to evaluate the current situation of the church, this research developed a pathological identification through visual inspection and IR thermography as a non-destructive technique. A numerical analysis was also performed by means of a nonlinear pushover analysis that allowed estimating the evolution of the damage and the capacity of the structure in a seismic event. The results of the analysis showed that the main failure mechanisms of the structure would be the decoupling of the church front portion (towers and choir), generating concentrated damage in the arches that support the choir, as well as longitudinal cracks in the nave walls. The seismic capacity related to these failures is around 0.20 g, which is much lower than the recommended demand from the Peruvian code for the region of Cusco – 0.25 g – meaning that the church is highly vulnerable to seismic loads.