A horrible statement that casts doubt on the power of God to preserve his word.
The truth is that Mark's gospel does not end abruptly but in verse 20. The vast majority of ancient manuscripts include all the verses.
The key to understanding the snake verse is in the context and the last words of the book. The words were addressed to the apostles (v 14) and not us today. The last words of the book says that the believers were confirming the word with signs following, one of them being living through deadly snake bites. God never asked men to believe new revelation without miraculous confirmation. The word is confirmed now so miracles have ceased (I Corinthians 13).
I don't believe that. Not that the Word was not confirmed, but that miracles have ceased.
To assert that they have is to assert that God's character has changed: God has been, and always be miraculous in nature. (Miracles being defined as God's direct interaction with the universe, esp in a physical way.)
There are many passages where God is directly portrayed as a lover and Israel/the-Church as his beloved; now factor in the distinctly male urge to impress his girl and rereading some of those passages and it seems obvious to me that God's saying "now watch this!"
In short, God still works in the Earth and in the lives of men, directly and indirectly.