Now it is ‘them’ again, because this verse is talking about the eleven, continuing from verse 14. So the structure is – verse 14 the disciples: ‘they’, then the promise: ‘he who believes will be saved’, then back to the disciples: ‘these signs shall follow them that believe.
The lesson of the passage is that we should always be believers in the providence and the promises of God. God’s promises are given in advance of our needs. He gives them because he knows we will need them to get through what follows. But if we do not embrace them we will flounder when we come to the trials that we have to experience. The arrest, trial, crucifixion and death of Christ was a great trial to them. It seemed to undermine all that they believed in, and yet a belief in the promise of the resurrection could have held them up through it all.
What were these signs that should follow? The apostles could do great things, the things that Christ did. Of course they would do even greater things (John 14:12): they would preach the gospel and by the power of Christ's Spirit thousands upon thousands would be converted. But the apostles were also given the power to heal the sick, to cast out demons, and, we read here, to even withstand the handling of serpents. Well, we saw that with the apostle Paul on one occasion when he was bitten by a serpent and simply was able to shake it off when all the observers thought he would surely drop down dead. We have no record in the New Testament of anybody drinking poison, any apostle. Perhaps it was so that one or two of the apostles may have been - but we are not told it - given poison to kill them, to execute them, and by the miraculous power of God survived it. These things were just for apostles for that time, because they were the witnesses of the resurrection and because they were also those who were the penman of Holy Scripture, the New Testament as it emerged and completed the word of God. They were therefore authenticated with certain signs, and the apostle Paul in addressing the Corinthians in 2 Corinthians – some of the Corinthians had doubted that he was an apostle – says, ‘Truly the signs of an apostle were wrought among you in all patience, in signs, and wonders, and mighty deeds.’ What do you mean Paul? Couldn't everybody do those things? No, says Paul. These were signs of apostles only. Only the apostles could do them.