When God told Adam and Eve in the Garden of Eden that they would surely die if they partook of the forbidden fruit, He did not mean that they would suffer immediate physical death.  On the contrary, He meant they would become separated from God which within itself is a fate far worse than any physical death could ever be.        

What we must first understand is that there are different types of death referred to in Scripture.  There is a physical death, which involves the separation of the inner man from the outer man leaving the body separated from the soul and spirit.  Then, there is a spiritual death, which God refers to in Genesis 2:16-17 when speaking to Adam and Eve.  In this regard, an individual can be spiritually dead but yet physically alive.

This condition also applies to the departed souls who are now dead in body but yet alive spiritually in the torments of Hell, awaiting God's "Great White Throne Judgment" which will include all lost souls from Adam to the end of the Millennium.  This will ultimately be known as the "second death" for all unsaved and eternally damned souls (Revelation 2:11, 20:6) who will be judged by God and rewarded according to their evil deeds done while in the days of their flesh (Revelation 20:11-15).

Apostle Peter stated, "The Lord is not slack concerning his promise, as some men count slackness; but is longsuffering to us-ward, not willing that any should perish, but that all should come to repentance" (II Peter 3:9).  Long ago Apostle John wrote, "Blessed and holy is he that hath part in the first resurrection: on such the second death hath no power, but they shall be priests of God and of Christ, and shall reign with him a thousand years" (Revelation 20:6).

Due to Adam and Eve's transgression against God's commandment Yeshua had to come to earth in the like figure of a man to suffer and die in order to buy back (redeem) from Satan what Adam and Eve so freely gave away.  Our eternal destiny then is determined by our faith and acceptance of Yeshua who provides an escape from everlasting damnation and separation from God.