You are quoting from Mark 16-20. Who is Mark? Believe what? Saved from what? What about the signs this Mark said would accompany this, such as "cast out demons", speak in tongues, pick up serpents, drink deadly poisons, heal the sick? And then there is the rest of the story.
Mark 16:16“He who has believed and has been baptized shall be saved; but he who has disbelieved shall be condemned.
17“These signs will accompany those who have believed: in My name they will cast out demons, they will speak with new tongues;
18they will pick up serpents, and if they drink any deadly
poison, it will not hurt them; they will lay hands on the sick, and they will recover.”