Are you referring to the upside-down cross? As an anti-christian symbol it doesn't refer to Peter, who was crucified upside-down for his beliefs. The logic behind the symbol is simple: If the cross represents Christ then a cross inverted by 180 degrees stands for the polar opposite of everything Christ represents.
I am just speculating, just because Peter was upside down doesn't mean the cross was. Two reason fir my speculation. 1) some believe that the cross may have resembled "T" more rather than "t". If this is the case then there wouldn't be the top section to place in the ground. But, it is said that a sign was hung (I believe it was even specified, which I could be wrong, that it was hung above Jesus head) that read, "King of the Jews." So if the sigh was placed above His head, that kind of throws out the "T" theory. So this leads to my next thought. 2) If the cross was shapes like a "t" then would there be enough upper part to put in the ground so that it would support the weight of a man? I would think no, because if the Peter was still placed on the cross as if he was to be placed right side up then they would also have to leave room for his head, which means even less cross being able to be placed in the ground which makes me doubt if there would have been enough support. Therefor I speculate that even though Peter was crucified upside down, the cross on which he was placed remained upright. This is assuming the legend of Peter being crucified upside down are true. Again I am speculating. God bless
Peter was never a good guy. According to bible's own claim Peter was a blatant liar & thus an imposture & Antichrist all through. Even Jesus himself branded Peter as Satan. You see that at "Matthew 16:23": Jesus calls Peter [a] "Satan" and "a hindrance," and accuses him of being on the side of men rather than that of God.
Lol. Or how about the Pentagram, which was a Christian symbol representing Jesus' wounds on the cross (head, hands, feet) inside a halo. (Though it was a Pagan symbol long before being a widely used Christian symbol.) We are a peculiar people indeed, and not in the same way we are supposed to be.
Its because its a catholic thing. Peter is/was a saint only in the eyes of the catholics who believe they can magic people into sainthood after the are dead (see the craziness). In reality Peter was a weak, flawed human loved by Christ anyway, not a saint or a pope. Heavy anti-catholic sentment in ages past turned the upside down cross into a symbol of the anti-christ and evil and this has been carried forth into modern days. Peter was a good guy but his death was horrific and catholics further sully his name and memory by trying to magic him into something he never was and is not now.