Well, the Nicene creed is a declaration of the Christian faith, as a whole. To deny the virgin birth, places Jesus in position of extraordinary man, not God, and implies that he was born into sin. The denial of the resurection of Jesus after death, clearly removes any Christianity from the faith.
So, I say yes, that is wrong (if one is insisting they are still Christian).
As far as declarations and Creeds are concerned, I don't agree entirely with the idea that you have to conform to everything in that declaration or Creed to be a Christian.
Life is a journey. In a journey we learn and discover things. What makes us Christian is that we have started the journey, because Christianity is about a journey.
Conformity dehumanises our existence because it demands that we adhere to the "cold logic" of a declaration or Creed. The idea of conforming to a declaration or Creed is plausible, but it's what a religious leader believes is essential to our journey, but not necessarily what God wants. Our relationship with God is more important than a declaration or Creed. The declaration or Creed is secondary.
Not everybody met Jesus in the same time or place, some met him in the market-place, some at home, some at a party, some in the desert and wilderness. Jesus said many words and in different times and places, and those words were potent and forceful. I don't deny that the words in the Bible are important, because the words in the Bible are potent and forceful. But he said these things in different situations and contexts. We can't go into our 21st-century reality and try to shoehorn some of the stuff in the Bible into the minds of our friends and family because it'd probably be taken out of context.
There is something more important than us chanting his words and dictating to non-adherents what to think and believe as if we know better because we are adherents of Christianity. Jesus said these things as part of a journey, the journey of the person receiving the words. If we are to properly understand the meaning of these words, we must receive them in the same way as the people received them in the story told in Scripture.
The trouble with declarations and Creeds is that they lack that original context. It makes being a Christian impersonal, which is what I mean by forcing someone to follow "cold logic." It is when we shoehorn a concept into their minds when they are not ready for it. But that doesn't mean they're not Christian. They have started the journey. But we, in our misguided understanding, think we know better than God how to live as Christians and shoehorn a declaration and Creed into their minds.
God is everywhere. Jesus could meet people anywhere. Yet when we force people to conform to a declaration or Creed, we forfeit the quality of "everywhereness" and "anywhereness" in a potential relationship with Jesus or God. We force people to meet God where we want them to meet God and that sabotages their relationship with God because they are not experiencing God in their own way. We are suppressing their individuality and spontaneity, and God made us all to be different. We should be letting people meet God in a way that He wants, not the way we want them to meet Him. That is what I think it means for us to be innocent like a child, that it opens the door for you to heaven. Don't follow the dictates of religious leaders, do what the child in you, the child of God in you says is right. -- and every child of God is able to defeat and defy the world, and the religious leaders are part of the world.
It is the journey, not the declaration or Creed that makes us Christian.
There are multitudes of interpretations. But actually if you think about it, the interpretation is more important and helpful to the interpreter himself than to the people listening to the interpretation. The interpreter is talking about how he sees his own journey but he can't really speak for the journeys of others.
For me, being a Christian is about reliving the journey of the first-century Christians and seeking the first-century experience, seeking to know what the first-century adherents possessed that we have long lost. There is no rule, declaration or Creed that makes us Christian. It's the journey, our dedication and devotion to the cause that makes us Christian.