Worst popular name for a scientific concept: "God Particle". Whenever you hear this, just think "Mass Particle" instead because it would explain why electrons, quarks, etc have mass.
This is still a simplification, but it's one billion times better than God Particle.
Physicists call it the Higgs boson. There is no empirical evidence that it exists, though it is predicted by theory. It is being actively searched for with the Large Hadron Collider. Finding it would further validate the "Standard Model" of particle physics. It's the only particle predicted by the Standard Model that hasn't yet been observed... hence it's "god-ness".
The More You Know.