Wherever I go, I see silly Christians with user names like Jesusfreak777, or 777godlover, etc.
You know the type. You've seen this before, or if you're a Christian, you might've even used it. This is NOT a Christian number. There are some Online references to the number 7 itself being Christian, and to symbolize Perfection, but the number 777 does not rival 666. It actually relates to it.
Aleister Crowley actually was one of the first to write about the number 777, with maybe exception of those who lived around 777 C.E. (That's 777 A.D. to you Christians).
The number 777 is popular amongst those either practicing Magick, or following Crowley's path of wisdom [PDF]. While it's used by ignorant Christians who have no sense of History, this idea that 777 is the holy, sanctified version of 666 is completely false.777 and other Qabalistic writings of Aleister Crowley is a collection of papers written by Aleister Crowley. It was edited and introduced by Dr. Israel Regardie, and is a reference book based on the Hermetic Qabalah.
Unrelated, 777 is also a good spin on the slot machines. Just saying...
My suggestion for Christians is to stop using this number, 777. It makes you either appear ignorant, or it makes you show an endorsement of the Adversary you fear.