Baptism and the Heart, Druids and Celtic Rite

I have some remarks on baptism over at Gornahoor, under the Clement series, but I'd like to note an interesting article which, along with Clement's journals, proves at the least that early Christians thought that baptism was more than a mere sign. Note Calvin and Luther's rejection of the ability of the finite to "bear the infinite"; they intended to defend the super-essence and pleroma of God over against the Baroque Uber-Kultur (which thought that God could be classicalized and painted pink, at its worst), but they ended up throwing out the baby of sacramental theology with the bathwater of excess and error.

I'll also note, in a related digression, that this article on Druidic invoking the elements reminds me a great deal of the Celtic rite in the Western Church. My question for John Michael Greer would be, if you are invoking the universal cross along with the triple spheres, how is this different from the Cross and the Trinity?