[jt8d]

The Holy Trinity, as I "understand" within limited human capacity:

Think of water. Water has three phases: vapor (gas), liquid, and solid (ice). All three phases are of one substance--the same molecule, which is H2O; however, each phase acts with distinctive properties, and each may exist apart from the others, or all at once in the same space and time. Oneness in substance, uniqness in character.

This is how I resolved the mystery in my very limited capacity as a creature of God.

[Salvation]

Your example of water
ice
vapor
liquid

is also a very good one.