Nowadays, the modal properties of structures can be obtained by experimental methods that are still expensive for professionals who have to deal with the seismic assessment. Additionally, for heritage buildings, due to their complexity, the identification of the modal properties can be challenging and requires of experience on the field. This paper aims to develop a methodology to predict the frequency response of churches based on simplified geometrical parameters. In this context, an extensive literature review was carried out to collect data, aiming to define the principal typologies of churches. Afterwards, a parametric analysis with numerical simulations of the eigenvalue problem was performed to identify which are the main geometrical parameters that influence the dynamic behavior of the churches. The correlations between the natural frequencies and relevant geometrical parameters are illustrated and discussed in order to develop a proposal for the estimation of the natural frequencies of the churches. Churches with single nave and three naves were defined as the two principal types of churches, and six equations were proposed, aiming to estimate the first three natural frequencies for each type of church. Finally, the methodology was validated on real case studies found in literature, in which experimental identification of frequencies was performed. This comparison allowed to evaluate the accuracy of the method to estimate the natural frequencies.