In Western society, the triangle most often has highly Christian meanings when used in a religious context. Because the Christian God is a trinity - Father, Son and Holy Ghost united in a single godhead – he is commonly represented by a triangle.
As a three-sided polygon, the triangle represents the number three, which is meaningful to many groups. As such, triangles and other symbols made of three parts may be used to present such concepts as past, present, and future or spirit, mind and body.
As a Summoning SymbolSome occultists use the triangle as a summoning symbol. At the culmination of a ritual, the desired being is expected to appear within a triangle inscribed upon the floor. The occultist often performs his ritual from the protection of a circle.
Point-up and Point-down TrianglesThe orientation of a triangle can be important to it's meaning. For example, a point-up triangle might represent a strong foundation or stability, as it is rooted to the ground through a solid base.
The elements of earth and water formed from point-up triangles, even thou these are the two more material elements. Symbols for air and fire are formed from point-down triangles.
The point-up triangle can represent male energy, and fire and air are masculine elements. The point-down triangle can represent female energy, and water and earth are feminine elements.
Read more: Alchemical Elemental Symbols
Point-up triangles can also represent ascension toward the spiritual world, while the point-down triangle can represent a descent into the physical world.
The uniting of a point-up and point-down triangle creates a hexagram.