9 When Jesus rose early on the first day of the week, he appeared first to Mary Magdalene, out of whom he had driven seven demons. 10 She went and told those who had been with him and who were mourning and weeping. 11 When they heard that Jesus was alive and that she had seen him, they did not believe it. 12 Afterward Jesus appeared in a different form to two of them while they were walking in the country. 13 These returned and reported it to the rest, but they did not believe them either. 14 Later Jesus appeared to the Eleven as they were eating; he rebuked them for their lack of faith and their stubborn refusal to believe those who had seen him after he had risen. 15 He said to them, “Go into all the world and preach the gospel to all creation. 16 Whoever believes and is baptized will be saved, but whoever does not believe will be condemned. 17 And these signs will accompany those who believe: In my name they will drive out demons; they will speak in new tongues; 18 they will pick up snakes with their hands; and when they drink deadly poison, it will not hurt them at all; they will place their hands on sick people, and they will get well.” 19 After the Lord Jesus had spoken to them, he was taken up into heaven and he sat at the right hand of God. 20 Then the disciples went out and preached everywhere, and the Lord worked with them and confirmed his word by the signs that accompanied it.
For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
The reason they do not like Jesus's last commands to the Apostles and are the last directions he gave them before ascending to Heaven. In Mark 16:15-16 he tells them " 15And he said unto them, Go ye into all the world, and preach the gospel to every creature. 16He that believeth and is baptized shall be saved; but he that believeth not shall be damned. KJV"
He clearly states that baptism is necessary for salvation belief + baptism = saved.
That goes against a lot of denominations plan of salvation, they teach a different plan than the Apostles taught. Hear is what the Bible teaches for salvation,
Hear- Romans10:17, Matthew 11:15, Acts 18:8.
Believe- John 5:24, Mark 16:16, Acts 16:31-33, Acts 18:8.
Confess- 1 John 4:15, Romans 10:9-10, Acts 8:35-38.
Repent- Luke 13:3, Acts 2:38, Acts 3:19, Matthew 9:13.
Baptized- Mark 16:16, Acts 2:38, Acts 8:5-13, Acts 8:35-38, Acts 9:17-19, Acts 10:47-48, Acts 16:13-15, Acts 16:31-33, Acts 18:8, Acts 22:16, Matthew 28:19.
Then God adds you into the Church- Acts 2:41, Acts 2:47, Colossians 2:12, Galatians 3:27, Romans 6:3-11.
Study the Scriptures daily- 2 Timothy 2:15.
Endure to the end- Matthew 24:13.