Unbelief

Mark 16:13 KJV
And they went and told it unto the residue: neither believed they them.

The word believe is a pretty major part of this chapter. The first thing that we learn is that when the disciples were told that Jesus had resurrected from the dead, they did not believe.

They did not believe when the women told them in verse 11
They did not believe when the two told them in verse 13
And in verse 14 Jesus "upbraided them with their unbelief."

But then Jesus entered into a curious message given their issues of unbelief.... He said
Mark 16:16 KJV
He that believeth and is baptized shall be saved; but he that believeth not shall be damned.

And then He said
Mark 16:17 KJV
And these signs shall follow them that believe; In my name shall they cast out devils; they shall speak with new tongues;

Salvation is based upon believing and
Power to be witnesses is based upon believing

So it is no light thing that they did not believe.

Thank God that saving faith is not something worked up by the Christian but is a gift of God which cannot be taken away. Once we possess saving faith, we can never lose that faith! On the other hand, lack of faith in the Christian should be a matter of serious and grave concern;
First because it can be an indicator that that person has never possessed true saving faith but only a man made substitute, and
Second because that Christian, if truly saved, can never be the witness to friends family and to the glory of God that he was meant to be without this faith.