In order to understand the concept of personal Salvation, some knowledge of the history of man's relationship with God is needed.  It's clearly stated in the Bible.

1) Mankind has a Problem.

When man was created by God, he was given freedom of choice.  Although God is all-powerful, and could have created a mere "puppet race", His power, love and mercy could never be shown in such a creation.  Man, with his "free will", chose to disobey God's word, and committed the species' first sin.  This sin resulted in a spiritual separation between mankind and God, and by the next generation, it spawned deceit and murder, when Cain killed his own brother, Abel.  This is an excellent example of how fast sin can overtake us.  We too, are the children of Adam, and we are inherantly separated from God by our very nature.  The Bible makes this clear in Romans 3:23:

"For all have sinned and come short of the glory of God."

We are separated from God and cannot enter into His glory and kingdom while we are sin-tarnished, since everything there is perfect and Holy.

Our problem is SIN.