An important factor in religious lectures as part of da'wah communication is the common language between da'i and mad'u. Language factor can inhibit delivery of da'i message to mad'u. This is because mad'u can understand the message of da'i in different ways. Therefore, this study is aimed to apprehend the differences in the use of da'i language and material understanding by mad'u. In particular, this study purposed to describe the way religious lectures with Javanese and mixed languages at the Nurul Huda Mosque. This study is also intended to explain the effect of the use of Javanese or mixture language towards an understanding of mad'u. This research used a qualitative approach. Data collection techniques used were observations, in-depth interviews, and documentation. The results revealed that religious lectures using Javanese were less effective among students and migrants. On the other hand, the mixed language used in religious lectures was very communicative and easily understood by the audience. In addition, different effects arose from the use of Javanese and mixed language by looking at the material conveyed by da'i to the understanding of mad'u. In this case, the understanding of mad'u matter became a benchmark against the effect that is generated from religious lectures.