At a wedding recently I used these symbols to illustrate the Great Mystery (Ephesians 5) of marriage. ​

​First the triquetra, an old Celtic symbol for the Trinity, God the Father, Son, and Holy Spirit. It also illustrates how Christian marriages invite God into our marriages, he strengthens the relationship like a threefold cord (Ecclesiastes 4)

But the Mystery of Marriage goes yet deeper:

1. (Tracing from the top to the lower left section)
   God the Father sent God the Son...
   
2. (to the top centre of the heart)
   ...to somehow open up the Trinity making room for us in eternity...
   
3. (to the bottom)
   ...Jesus came to us in human form, took our sin on his body on the cross, died for it in our place, to make us right with God, & rose again to show he defeated sin/death...
   
4. (up to the top left of the heart)
   ...then he ascended into heaven where he is preparing a place for us even now...
   
5. (to the lower right section)
   ...He sent his own Holy Spirit, to be within us, whatever we're going through...
   
6. (return to the top)​
   ...And one day he will take us to be with Him in Heaven forever!
   

True North - Christian
From hiking to ethics, politics, spirituality, psychology, relationships, in all areas of life in which decisions about reality are important, we really need a true reference point. We need the compass needle to point north so we can align ourselves with reality as it is, and not get lost. A reliable reference point. 
For societies to function well together, a primary reference point needs to be agreed so we can all avoid conflict as much as possible. When I visit Indonesia, I know the local reference point is largely Islam, so I know how to get along. Even if I don't agree with Islam personally, I can accomodate wherever possible in good conscience. At Australian Federation we chose a generally agreed reference point in Judaeo-Christianity, the Bible, "under Almighty God." The consensus was that we all go along with this same reference point as a society. Besides, part of that Christianity was that "secular" meant non-sectarian, open to all, regardless of creed. So Christianity provided a good reference point for public ethical decisions and the moral conduct of society. 

Spinning Compass - Agnostic
​But from mid twentieth century, Australia's general population became less certain of Christianity, and even the idea of objective truth. With growing multiculturalism, the magnets of other ideologies made the public discourse agnostic: "we don't know what our public reference point should be." But instead of really thinking this through, broadcast technology rushed through the shallow, political-correct (ie. wrong in the real world) idea of "each to his own, you do you, I'll do me." Public media and politics mostly ignored the matter of truth, ultimate reality, or an agreed reference point.
This sounded democratic: "let's leave it as a private matter and not have a public reference point as such." But it only leads to power-plays: "whose point of view will rule." That's why although most Aussies (and governments) still think no reference point is what we have today, it's not so...! 

Self-Aligned Compass - Naturalism
Most of us ​didn't even see it happen and assume we're back at Agnostic. But to the degree that religious/spiritual worldviews are excluded from the public square, one worldview stands deceptively as the default reference point. Naturalism asserts there is only the natural, physical world, no super-natural, no other dimensions, no God to answer to, no higher power, so do anything you want - just keep religion private. "Secular" has come to mean, "no religious views." In practice this Naturalism is Australia's public reference point now, unofficially determining all our national, ethical, political decisions. Decisions about marriage, gender, religious education, terminating babies & the infirm, public narratives about science, climate, race, power/victim status, are all decided squarely on the reduced basis of Naturalism. All spiritual considerations are excluded.

We were never asked if we wanted to shift our public reference point at all, let alone shift it to Naturalism. It just happened by excluding the other options. If we had been asked, "Do you want Naturalism as our new public reference point?" we would have certainly voted against it. Why?
1) Partly because more of us do experience spiritual realities than do not. "Under God" is a real consideration for most of us.
2) Also because with a little thought it soon becomes obvious that Naturalism is a really bad reference point because it inevitably leads to the Law of the Jungle, with everyone pulling for their own interests, with the most ruthless grabbing power to eliminate the competition. That's been the result in all socialist / communist governments, which are always based on, yep, Naturalism. We know where that road leads, and we don't want to go there.