Thankfully not, according to this online quiz, which asks you some finely shaded questions about what you believe (about sin and the divinity of Jesus) and then compares it to the creed of the Council of Chalcedon, held in 451. I passed!
You scored as Chalcedon compliant. You are Chalcedon compliant. Congratulations, you're not a heretic. You believe that Jesus is truly God and truly man and like us in every respect, apart from sin. Officially approved in 451.