In Mark 16:16, we read the following:
He that believeth and is baptised shall be saved; but he that believeth not shall be damned.
This verse has been used by Latter-day Saints as pretty strong evidence of baptism being salvific, as Christ ties both faith and baptism into the “requirements” of salvation. However, there has been much scripture-wrenching to avoid this conclusion. Evangelical critics of LDS soteriology have argued that, since damnation is tied into disbelief, with no reference to not being baptised, Jesus is teaching faith alone saves, and that baptism is a symbol thereof.
Needless to say, such is an utterly pathetic response. It is true that damnation is associated with disbelief, without reference to baptism. However, such a "counter" fails to deal with the fact that salvation is tied to both belief and baptism, as previously mentioned. The reason for the absence of baptism in the second clause of Mark 16:16 is due to the rather simple fact that if one does not believe, they will not be baptised. However, baptismal regeneration is clearly taught with the greatest of perspicuity in this text due to belief and baptism being associated with salvation.
On the issue of the authenticity of Mark 16:9-20, the so-called “Longer ending of Mark,” this pericope was known to the authors of Luke, 1 Clement, the Shepherd of Hermas, and, assuming the priority of Mark, Matthew, and other early Christian authors, and a solid case can be made for their authenticity. See Nicholas P. Lunn, The Original Ending of Mark: A New Case for the Authenticity of Mark 16:9-20 (Pickwick Publications, 2014).