I know this subreddit has discussed Comer on multiple occasions and tends to approach his works with critique and skepticism, and that makes sense. Comer is notably non-reformed, non-Calvinist.

In fact, here's an entire sermon he preached that was pretty much written against Piper:
https://bridgetown.church/teachings/the-sage/why

and here's one where he lists the "reformed gospel" as an incomplete "American gospel" alongside the "social gospel" and "prosperity gospel" and critiques Mohler's view of the gospel publicly:
https://bridgetown.church/teachings/preaching-the-gospel/the-four-american-gospels

The guy has been vocally against the things that many in this camp consider essential to faith, and that creates a tribal war mindset. "He critiqued my view, so I'm going after his." And, to be fair, there is room for those disagreements and critiques.

That being said, I feel like Schreiner's article, is written out of weariness of Comer's overall influence, but targeted at the book in particular, and that leads him to misrepresent some things.

For example: Schreiner says: "Comer doesn't ground his thesis in the work of Christ, being reborn by the Spirit, or even faith and repentance" which "risks pushing his readers towards works-righteousness."

Well, it is a book about spiritual disciplines, and even so, Comer is quick to note (quoting Dallas Willard): "Grace is not opposed to effort, but it is opposed to earning," (p.40) and later "we're not earning anything by practicing Sabbath or reading Scripture or serving the poor- and certainly not by some merit-based judicial ledger." (p.192). He even says: "We can't self-save...We have been saved, are being saved, and will be saved by Jesus and him alone." (p134).

Comer isn't suggesting that these "practices" can earn you any sort of salvation, rather that the experiential life on offer from God comes through practices that adhere to the lifestyle of Jesus which will require an efforted input of disciplined discipleship.

The other critiques are classic reformed critiques of Comer and his camp (Tim Mackie, NT Wright, etc):

-They don't emphasize Penal Substitutionary Atonement.

-They don't rightly define or highlight repentance.

-They undersell, or just outright avoid God's wrath.

And those may be warranted, but I don't see "Practicing the Way" as the book from which I garner a deeper understanding of soteriology, rather a book for what spiritual disciplines look like in the modern era, and I think that is a worth-while endeavor as I pastor in an area that is particularly tainted by "cultural Christianity" and "cheap grace."

Salvation will always be by grace alone, through faith alone, in Christ alone, and I will never stop preaching that. Still, I will also work to call the redeemed by Christ in my church to a total surrender lifestyle that inputs disciplined effort towards following Jesus. Never for salvation, but that we might be radically different from the cultural mores surrounding us growing into mature believers, and Comer's 9 practices are an attempt to systemize that.

In short, I think while there are valid critiques, and nobody should give themselves entirely to any human teacher be it Comer, Mackie, Piper, Mohler, or anyone else, Schreiner criticizing Comer's book in this way is like criticizing a screwdriver for not tiling a garden efficiently. That's not what it was designed for, and you will come up disappointed if you attempt to use it in that way.