16 He that believeth and is baptized shall be saved; but he that believeth not shall be damned.
[AD 380] Apostolic Constitutions on Mark 16:16
And again: "He that believeth and is baptized shall be saved; but he that believeth not shall be damned."

[AD 430] Augustine of Hippo on Mark 16:16
The ecumenically received faith is taught in the creed and committed to memory in a form of the utmost possible brevity, so as to frame an expression in few words of that which was intended to be explained at large afterwards to persons in a state of formation and advancement in knowledge of God.

[AD 430] Augustine of Hippo on Mark 16:16
We know that the dead who die in the Lord are blessed, and they have no concern with what they would have done if they had lived a longer time. We know that those who believe in the Lord from their own heart do this of their own will and free choice. We who now believe act rightly when we pray to God for those who refuse to believe, and pray that they themselves may in time freely will to believe.

[AD 604] Gregory the Dialogist on Mark 16:14-18
(ubi sup.) We should observe that Luke says in the Acts, As he was eating with them he commanded that they should not depart from Jerusalem, and shortly afterwards, while they beheld he was taken up. For He ate, and then ascended, that by the act of eating, the truth of the flesh might be declared; wherefore it is also here said, that he appeared to them for the last time as they sat at meat.

(ubi sup.) Another reason also why our Lord rebuked His disciples, when He left them as to His bodily presence, was, that the words which He spoke on leaving them might remain more deeply impressed upon the hearts of His hearers.

(ubi sup.) After rebuking the hardness of their hearts, let us hear the words of advice which He speaks. For it goes on: Go ye into all the world, and preach the Gospel to every creature. Every man must be understood by every creature; for man partakes something of every creature; he has existence as have stones, life as trees, feeling as animals, understanding as have Angels. For the Gospel is preached to every creature, because he is taught by it, for whose sake all are created, whom all things are in some way like, and from whom therefore they are not alien. By the name of every creature also every nation of the Gentiles may be meant. For it had been said before, Go not into the way of the Gentiles. (Matt. 10:5) But now it is said, Preach the Gospel to every creature, so that the preaching of the Apostles which was thrust aside by Judæa, might be an assistance to us, since Judæa had haughtily rejected it, thus witnessing to her own damnation.

(ubi sup.) But perhaps some one may say in himself, I have already believed, I shall be saved. He says what is true, if he keeps his faith by works; for that is a true faith, which does not contradict by its deeds what it says in words. There follows: But he that believeth not shall be damned.

(ubi sup.) Are we then without faith because we cannot do these signs? Nay, but these things were necessary in the beginning of the Church, for the faith of believers was to be nourished by miracles, that it might increase. Thus we also, when we plant groves, pour water upon them, until we see that they have grown strong in the earth; but when once they have firmly fixed their roots, we leave off irrigating them. These signs and miracles have other things which we ought to consider more minutely. For Holy Church does every day in spirit what then the Apostles did in body; for when her Priests by the grace of exorcism lay their hands on believers, and forbid the evil spirits to dwell in their minds, what do they, but cast out devils? And the faithful who have left earthly words, and whose tongues sound forth the Holy Mysteries, speak a new language; they who by their good warnings take away evil from the hearts of others, take up serpents; and when they are hearing words of pestilent persuasion, without being at all drawn aside to evil doing, they drink a deadly thing, but it will never hurt them; whenever they see their neighbours growing weak in good works, and by their good example strengthen their life, they lay their hands on the sick, that they may recover. And all these miracles are greater in proportion as they are spiritual, and by them souls and not bodies are raised.

[AD 735] Bede on Mark 16:14-18
(ubi sup.) What shall we say here about infants, who by reason of their age cannot yet believe; for as to older persons there is no question. In the Church then of our Saviour children believe by others, as also they drew from others the sins which are remitted to them in baptism. It goes on: And these signs shall follow them that believe; In my name shall they cast out devils; they shall speak with new tongues; they shall take up serpents.

[AD 1107] Theophylact of Ohrid on Mark 16:14-18
Or else; to every creature, that is, whether believing or unbelieving. It goes on: He that believeth and is baptized shall be saved. For it is not enough to believe, for he who believeth and is not baptized, but is a catechumen, has not yet attained to perfect salvation.

That is, they shall scatter before them serpents, whether intellectual or sensible, as it is said, Ye shall tread upon serpents and scorpions, which is understood spiritually. But it may also mean sensible serpents, as when Paul received no hurt from the viper. There follows: And if they drink any deadly thing, it shall not hurt them. (Luke 10:19) We read of many such cases in history, for many persons have drank poison unhurt, by guarding themselves with the sign of Christ. It goes on: They shall lay hands on the sick, and they shall recorer.

[AD 1274] Pseudo-Jerome on Mark 16:14-18
But in a mystic sense we may understand that faith here labours, leading the active life, but there it reigns secure in the contemplative vision. Here we see His face through a glass, there we shall see the truth face to face, wherefore He was shown to them as they were walking, that is, labouring, in another form. And when it was told, the disciples did not believe, because they saw, like Moses, that which was not enough for them, for he said, show me thyself; (Exod. 33:18. Sept.) forgetting his flesh, he prays in this life for that which we hope for in the life to come.

But He appeared when all the eleven were together, that all might be witnesses, and relate to all men what they had seen and heard in common. It goes on: And upbraided them with their unbelief and hardness of heart, because they believed not them who had seen him after his resurrection.

But He rebukes their want of faith, that faith might take its place; He rebukes the hardness of their stony heart, that the fleshy heart, full of love, might take its place.

[AD 1274] Glossa Ordinaria on Mark 16:14-18
(non occ.) Mark, when about to finish his Gospel, relates the last appearance of our Lord to His disciples after His resurrection, saying,1 For the last time he appeared unto the eleven as they sat at meat. (Acts 1:4, 9)