In the Gospels, we find a term that’s an emic category—parousia. We find it in the world of the text παρουσια, a Greek Word meaning “presence” or “coming.” In the New Testament, it’s almost always used in reference to Jesus’ second coming.
An etic category might be the Trinitarian theology of Matthew’s Gospel. Matthew never uses the word trinity. In fact, the Latin trinitas originated with Tertullian, the early church father. The New Testament authors didn’t use the term trinity or have that concept. (Jeremiah J. Johnston, Body of Proof: The 7 Best Reasons to Believe in the Resurrection of Jesus—And Why It Matters Today [Minneapolis, Minn.: Bethany House, 2023], 81, emphasis in bold added)