^^^
I have asked you to quote from Quraan what you are saying. Read Sura Furqan and Ayat 68, then quote reference where these sins will be forgiven. Otherwise don't misguide people here.
You can not mold the strict criterian set by Allah in Holy Quraan. e.g. if so called Taliban or anyother entity kill innocent people, do you think Allah would forgive them or you do prostitution, gang rape, involve in pornograghy of minors, fornication or adultry and Allah will forgive you? Keep in mind what Allah has ordered in the Holy Quraan.
Hazrat Umar's son committed adultry and Khalifa e Waqt ordered 100 lashes for his son. After 50 lashes his son died, he ordered continue with the lashes on dead body till 100 were completed so that his son would not be punished in the hereafter. This is how the real Muslims were obeying Allah's laws in the past.
I read Surah Furqan, Ayat 68 - it does not say anywhere that these select sins are unforgivable. Nothing of the sort is mentioned. But what is puzzling is that while you say so, you've quoted an account of a man who was forgiven for adultery in your third point of contention.
By the way, lashes are the punishment for fornication (not adultery).