Here is an explanation of the Free Gift

Let’s start from the beginning....

The Bible explains that the reason we have so many problems in this world is that we are sinners. We are all sinners, every one of us. We have in us what is called the "sin nature". This means you do things that are wrong in God’s eyes. The definition of sin is to miss the mark. As in archery when you miss the bullseye. So it is different than what you might have been taught by worldly philosophies. We actually are not born inherently good. Though we are born with a conscience (which helps us determine right from wrong) we are also born with the "sin nature" in us at birth which is bad.

"All have sinned and fall short of the glory of God..." - Romans 3:23

Even if you are a pretty good person and do things that are mostly good, in God's eyes you are still the same: a sinner. In fact, God says there is no good person in the whole world who does not sin.

"For there is not a just man on earth who does good and does not sin." - Ecclesiastes 7:20

Being that God is Holy and perfect, He cannot allow sin to enter into His presence in Heaven. It would be like defying the law of gravity here on earth. It just can't be that way. So in other words, sin is what keeps us from going to Heaven.