This symbol is called a Triskele and is often reffered to as a the three-legged Swastika.
It was aopted by the Nazi's and is used as the flag of the extremist white supermacist group
Afrikaner Weerstandbeweging (AWB) in South Africa.
The three sevens which are the supposed numerical value of YAHWEH
(or G
od in Abrahamic religion) and opposed to the anti-christ number of 666.
777 represents the anti-anti-christ.