I have a birthmark that looks like 666. Am I going to hell?

Question

It's on my left leg, just below my knee.

Answer 1

Since you are referencing the number 666 (as it is mentioned in the Book of the Revelation in the Bible), I will assume you are asking this question form a Christian point of view.
The answer is that whether or not you go to Hell is up to you. No matter what birthmark you have, you are a sinner just like the rest of us. And just like the rest of us you are condemned to die and go to Hell because of that sin.
But God came to earth and took on flesh in the form of Christ. He lived, laughed, cried and suffered as any of us might do, except that He committed no sin. So when He was put to death on the cross, His blood was innocent and pure. He became the ultimate sacrifice and paid the debt of sin for all time.
So just like a "get out of jail free" card, there is a way to avoid Hell. But you have to play the card. Jesus asks only that you confess and repent from your sins, ask forgiveness, and trust Him and follow His teachings.
If you do those things, then you will not go to Hell in spite of your birthmark.