15 And he said to them, “Go into all the world and proclaim the gospel to the whole creation. 16 Whoever believes and is baptized will be saved, but whoever does not believe will be condemned.

Great verses. Some like to believe that only John 3:16 is necessary to be saved and ignore the fact that baptism is also a necessity as well. Verse 16 above shows that baptism as well is a necessity. The word "and" shows that we must believe and be baptized. Of course we must then live faithfully. A ticket into heaven is obtainable for every single human, but we must obey and stick to all of God's word.

Mark 16:15-16
King James Version
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.

John 3:16
King James Version
16 For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.