Religio is a term used to show the strength of a bond between those who say it.
The word is a close cousin of religion, which is taken from the latin religio, which means to bind, explaining the roots of the word.
If one friend says "religio" to another, it is a manly way of showing your appreciation and respect of their friendship. The louder it is said, the greater the level of respect.
It is an it or cult phrase in many parts of Australia and is slowly spreading its sphere of influence globally.
That's the power of Religio.