This chapter has quite a few instances where these and those have been mixed up in the history of the text. There are three examples where the mix-up occurred in the manuscripts (see the examples discussed under verses 11, 16, and 20). Here in verse 27 we have a case where the 1906 LDS edition made the switch, in this instance from these to those. Since this edition was never used as a copytext, subsequent LDS editions have retained the correct these.
Summary: Maintain the original these in Alma 57:27: “now this was the faith of these of which I have spoken”.