Islamicate refers to the cultural and social practices that are influenced by Islam, but are not necessarily religious in nature. Think of it like this: if Islam were a tree, then Islamicate would be the branches and leaves that grow from that tree.
For example, Arabic calligraphy is a form of Islamicate art. While it may include religious texts, it is primarily appreciated for its aesthetic and cultural value. Similarly, the tradition of drinking tea in Muslim countries is a form of Islamicate culture, but it may have little to do with religious beliefs.
So, Islamicate is a term used to describe the ways in which Islam has influenced the broader culture and society in which it exists. It's a way to recognize and appreciate the diversity and richness of Muslim societies, even beyond the religious sphere.