There is a way in which doubt can establish faith rather than undermine it.
Let’s suppose for a moment that Jesus did not rise from the dead. Some people believe that and the way they explain the Biblical accounts is to say that years later they were written by manipulators in order to turn a good teacher into a god to galvanize a movement that was beginning to fray.
There are historical, theological, and textual problems with this answer, but let’s leave them aside for the moment and ask what kind of writings such manipulators might manufacture. How would they tweak history to convince people 100 to 200 years later (according to skeptical timelines) that Jesus came back to life?
You might put words in Pauls mouth to the tune of:
“He was raised on the third day in accordance with the Scriptures, and that he appeared to Cephas, then to the twelve. Then he appeared to more than five hundred brothers at one time, most of whom are still alive, though some have fallen asleep. Then he appeared to James, then to all the apostles. Last of all, as to one untimely born, he appeared also to me.” (1 Cor. 15:4-8)
Years after Paul’s death there would be no way to actually verify any of this. These writings would be taken as inspired scripture which you’re not allowed to question so there you go. Jesus rose even when he didn’t.
I’m giving the skeptic a lot of leeway here. There are problems with the idea of anyone accepting modified writing or with their sudden appearance 200 years later if they were made up. But let’s let them have those for now.
A more sophisticated approach might be the story of Thomas’ doubt in John 20:26-29:
Eight days later, his disciples were inside again, and Thomas was with them. Although the doors were locked, Jesus came and stood among them and said, “Peace be with you.” Then he said to Thomas, “Put your finger here, and see my hands; and put out your hand, and place it in my side. Do not disbelieve, but believe.” Thomas answered him, “My Lord and my God!” Jesus said to him, “Have you believed because you have seen me? Blessed are those who have not seen and yet have believed.”
You see? Thomas came around! A story like, were it fake, would serve to strengthen the deception. “See? Thomas didn’t believe it either! But Jesus said you’d be blessed it you believe without seeing.”
What you would not expect to see if people are trying to establish the lie that Jesus rose from the dead and everyone back then knew it and believe it is this:
Now the eleven disciples went to Galilee, to the mountain to which Jesus had directed them. And when they saw him they worshiped him, but some doubted. (Matt. 28:16-17)
These supposedly fabricated stories would seek to establish the supposedly ancient truth that Jesus rose and people saw him. Why would they include this? The disciples saw the resurrected Jesus and they worshipped him. “But some doubted.” What more proof did they need? He’s standing right in front of them!
But Matthew’s account could serve to undermine the entire covert attempt to fool people. You can’t let that kind of doubt slip through or the whole thing could unravel on you.
So why did Matthew include it? Probably because it really happened. People are not so simple as to believe just because they have evidence. We all doubt sometimes and the disciples were no different. After all, people don’t usually rise from the dead. Even in the pre-scientific mindset of the first century, Lazarus rose from the dead because Jesus told him to. But Jesus just rose.
That leads to another problem with fabricating this story. Even by the third century, women were not given equal status in society. So when the gospels say that women reported that Jesus rose, it again kind of undermines the attempt at deception.
So is it satisfying to believe that these masterminds who attempted to turn Jesus into something more than a rabbi were genius enough to fudge the scriptures and at the same time dopy enough to do it so poorly? It isn’t to me. So even when I question and wonder and, yes, doubt I still look at the scriptures and believe. But some doubt.