How can you say that death is not the consequence for sin whereas the Bible clearly teaches that it is?
Many people misunderstand this story to mean that physical death is a consequence for sin. But the biblical scholars who are aware of all its implications explain otherwise. The Interpreter's One Volume Commentary on the Bible explains that death here means separation from God, the giver of "life" (p.6).
The reason for this other explanation is the obvious fact that in the story Adam did not die. He lived on for 930 years (see Genesis 5:5). And when God spoke of his eventual death, He mentioned it not as a consequence of sin, but as a natural outcome of the fact that Adam was created from dust - and to dust he must return (see Genesis 3:19).
When a few verses later it is stated that God deprived Adam in access to the tree of life many people again conclude that because of sin Adam was deprived of everlasting life. But this too is not what the book of Genesis says. The story goes that once Adam gained knowledge of good and evil, God was concerned that he may now gain eternal life also (see Genesis 3:22). The Abingdon Bible Commentary explains that Adam was deprived of eternal life because he had already acquired some power, namely knowledge, and God was concerned lest Adam should acquire more, namely eternal life, and become a threat to God (see the Abingdon Bible Commentary, p.223).
It is clear from the story that even if Adam was promised death he was given a lesser penalty, and death must be taken as the maximum possible penalty - that, obviously, was not given. Elsewhere in the book of Genesis, when God killed certain men for their wickedness, it meant instant death (see Genesis 38: 7, 10). But the death that comes as the natural end to physical life is not a penalty for sin. It is better to understand that God in His mercy gave a lesser penalty to Adam than to suppose that God in His anger gave more penalties in addition to what He stated initially. This is why Reverend W. K. Lowther Clarke explained in his Bible commentary that God relented and gave Adam a lesser penalty (see the Concise Bible Commentary 1952, p.343). For the Qur'anic perspective on the Genesis story, see question 17.