Woofgang, According to Islam the only person who will never go to heaven is the one who either does not believe in God or associates a partner with him. According to Quran this is something that God will not forgive. Belief in the oneness of God is the minimum and most important factor. However a person would still have to be answerable for what they did in this world. Unless a person repents as soon as he/she realises that he has done wrong. Allah can forgive whatever he wishes if a person asks for forgiveness. But on small chapter in Quran sums up completely that what a person has to do to be successful. And here it is.
In the name of God, the Gracious, the Merciful.
1. By Time.
2. The human being is in loss.
3. Except those who believe, and do good works, and encourage truth, and recommend patience.