Bahá’í Sacred Writings, ‘Abdu’l-Bahá, #433

Thou hast asked about places of worship and the underlying reason therefor. The wisdom in raising up such buildings is that at a given hour, the people should know it is time to meet, and all should gather together, and, harmoniously attuned one to another, engage in prayer; with the result that out of this coming together, unity and affection shall grow and flourish in the human heart.