We are told in Acts that thousands of Jews were converted in one day.
We might be told that, but it doesn't mean it is true.
And why would anyone believe such an implausible claim knowing that christianity failed to gain a foothold in Palestine. If christianity was really gaining thousands of new converts a day it would undoubtedly have swept all other religions aside. In fact at that rate the entire population of Palestine would have been converted in about a year.
This is another of the exaggerated and hyperbolic claims which don't add to the credibility of the new testament - rather they critically undermine it.
And just as an aside, how on earth would they count these 'new converts' - as far as I'm aware they didn't have membership lists in 1stC Palestine.
The bottom line is that were the claims in the gospels and acts true then it is simply impossible to countenance that christianity wouldn't have rapidly become the dominant religion in 1stC Palestine, in other words amongst those purported eye witnesses to those claimed events. That it didn't tells you everything you need to know about the credibility of those claims.