A movement is a TruthMovement if it follows the scientific method for establishing which ideas are most true (i.e., which concepts best model observable reality). Sadly, this method is still rejected by most of the religious creeds of the world--but humans are adaptable, and many great scientists have also been deeply religious people.
The SolSeedMovement is a TruthMovement. Although the SolSeedCreed is written so that it can be added without conflict to any kind of faith (see SolSeed and Religion), SolSeed mainly seeks to find spiritual value and purpose in the world as we empirically know it. We talk about Gaia, a controversial scientific concept, and about a Destiny that sounds like a prophecy, but we admit that these are stories, not knowledge. We believe in the Destiny as a worthy and inspiring goal and Gaia as a useful and inspiring metaphor, but what we believe to be true (or rather, as close to the truth as we can presently get) is based around mainstream science.