Not at all my friend. If you understood MK16, you would see that the signs followed those who believed...Believed the Apostolic preaching, thank you very much for proving my point.
It helps to read the whole passage, not pull out a phrase or two;watch;
14 Afterward he appeared unto the eleven as they sat at meat, and upbraided them with their unbelief and hardness of heart, because they believed not them which had seen him after he was risen.
15 And he said unto them, Go ye into all the world, and preach the gospel to every creature.
16 He that believeth and is baptized shall be saved; but he that believeth not shall be damned.
17 And these signs shall follow them that believe; In my name shall they cast out devils; they shall speak with new tongues;
18 They shall take up serpents; and if they drink any deadly thing, it shall not hurt them; they shall lay hands on the sick, and they shall recover.
19 So then after the Lord had spoken unto them, he was received up into heaven, and sat on the right hand of God.
20 And they went forth, and preached every where, the Lord working with them, and confirming the word with signs following. Amen.
There you go, read it 5 or 10 times in a row, then you will see it!
What else do you have brother?