The Trinity is a rational doctrine, which can be understood by selecting facets of one aspect of a creature, another facet from creation, and yet another from somewhere else in this world. Then, the necessary step to make it “rationally conceivable” is joining these disparate features from within creation and seeing them together. I am not advocating that the Trinity can be divested of its mystery, but I am contesting the notion that the doctrine of the Trinity is absurdity or inherently contradictory.
With this said, Genesis 1:27 – 28 and Genesis 2:24 point out that God’s self-chosen analogy for Himself is the human family. We first find that both “male and female” constitute the “Image of God” (Imago Dei). These two, who constitute God’s image, are to “become one flesh,” which is an activity representative of the “Image of God.” Yes, sex is representative of God although sadly bastardized into a solely unclean thing in our culture.
Man and woman produce offspring: this child is the active union of the mother and father. Moreover, children exhibit characteristics of his/her parents whether or not he/she has ever met his/her parents. Nurture is not the source, therefore, of a child’s likeness to his/her parents; nature is. Striking indeed is that a woman and a child share the same space while the woman is pregnant with the child. The father, of course, is manifest in the child as well since his very being (genetics) comprises this child together with the wife. So what do we have? We have one person, the child, who is of the same nature as the parents (genetics/biologically), one person (child) sharing the same space as another person (mother), and, lastly, the mother and child are distinct persons.
Thus, in the very being of the child, the father and mother are present, both biologically and in character traits — although it will take many years to see this clearly. A pregnant woman might be the best analogy for the Trinity, requiring the least amount of adaption.
The Trinity is three distinct Persons who completely share the same “divine space,” and who are one in nature; a pregnant woman represents two distinct persons who share the same space (not completely though), and who are one in nature with even the third person (father) represented.
Conclusion: God self-chosen analogy gives the best representation found in a singular place, and that analogy is male and female involved in the procreational process, i.e., sex.