Should Mark 16:16 Not Be In The Bible ?

Because Mark 16:16 teaches so clearly that baptism is necessary to salvation, many say Mark 16:9-20 is not in two of the three oldest manuscripts (Sinaitic and Vatican), so Mark 16:16 shouldn’t be part of the Bible, and therefore cannot be used as proof that baptism is necessary to salvation.I don’t believe that for one minute!:● The passage in question is in one of these three oldest manuscripts (the Washington).● It is quoted by men such as Irenaeus and Hippolytus two to three centuries before these oldest manuscripts were written.● There were at least ten translations done before these oldest manuscripts were written, all of which contain the passage in question.● The Vatican manuscript ends at Hebrews 9:14. Do these naysayers reject this whole section of scripture also?I Peter 1:25 says “the word of the Lord endureth for ever.” God does take care of his word.