I'm looking for a Symbol that can refer to "this is the path to Heaven" or this is the path to Hell"

If you wang a symbol, ying& yang

Sounds like you are touching on an "as above, so below" type of symbol although they don't exactly refer to taking this path our that path. Examples include The Star of David which to most represents Judaism but to an occultist is one triangle pointing up to God and the other down to hades.

Perhaps consider an image of a man standing, taking an oath with his right hand palm out (like when people promise to tell the truth in court) but his left hand is partially or wholly tucked inside his jacket over his heart, like you may have seen Napoleon do in paintings. The "Right Hand Path" = good versus "The Left Hand Path" = sinister evil which is often committed in secret, hence the hand being obscured within the jacket (aka The Hidden Hand).

For plain symbolism you could use a black gloved left hand and a white gloved right hand. Other occultists would clearly know.