The third day of Christmas and we have two options - so here's the first of them in the shape of the Trinity. So, leaving aside the idea that God might be green with three leave (thanks to the good old Shamrock) and so many other modalism, multiple personalities and the other confusions, let us try a bit of sound theology (again) as we revisit past thinking:
The Trinity is a simple concept in that God (the Father) is the author of life and of our reconciliation (salvation) to Him. God (the Son) is the means by which that reconciliation with God is effected by the freewill submission to death on the Cross for each of us. God (the Holy Spirit) lives in us and guides us to maintain that relationship and live within the salvation reality that is open to us. (of course we tread a fine line here!)
One of the clever devices that comes from the early church is the little drawing that puts it simply and graphically so we lame brains can grasp it:
Of course we can get more into this and head for Nicea (325AD) and get to grips with the 'substance' (ousia) and we find that God, Father, Son and Holy Spirit are one ousios (homoousious), not similar (homoiousious), not different (heteroousios). One subtance, three distinct and separate wills - all in accord.
So here's your 'third day' present - a cool diagram :-)