And Really, as much as its silly to deny hell, It is ever so foolish to deny oneself heaven.
Heaven cannot exist without casting a large number of evil people into hell, Ask the child who's been wronged by a pedophile, or a child who's got no idea who his parents are, or the mother whose little babies get murdered in cold blood, the list is endless!
How can anyone in his senses Not believe in Hell and actually think that ALL sorts of sick people will live in Heaven? Cant even begin to think how Kind these people think themselves to be, why don't they just go live in a penitentiary or a guanatamo bay or a terrorsit camp ,hope they'll get the gist of reality in time.
And yes, The concept of Allah (One God) In Islam is not only much sensible, but also More Magnanimous and Kind beyond any Human's perceptive capability. He's Kind to all, even those who do not believe in Him and those who assign Him partners,or deny His existence. And yes, He has forewarned All ,for those who were given a chance to grasp that reality, beleived in it rather than turn their face the other way.
And in this day and age Nobody can deny that they never heard of Him or never got to know the message of Islam. May Allah guide us all to the truth, Ameen.