How do the 3 Protestant traditions deal with the two types of sin mentioned in 1 John 5:16-17?

When reading the letters of John the other day I was struck by [1 John 5:16-17](https://www.biblegateway.com/passage/?search=1%20John%205%3A16-17&version=ESV) : > ¹⁶ If anyone sees his brother committing a sin not leading to death, he shall ask, and God[a] will give him life—to those who commit sins that do not lead to death. There is sin that leads to death; I do not say that one should pray for that. ¹⁷ All wrongdoing is sin, but there is sin that does not lead to death. To me this is a very straightforward and a plain indicator of the two types of sin distinguished by no lesser authority than the apostle John himself. The Catholic tradition calls the two types of sin *venial* (don't lead to death) and *mortal* (lead to death), with an accompanying detailed teaching on how to distinguish them and how to deal with them. See [this article](https://catholicstraightanswers.com/what-is-the-difference-between-mortal-and-venial-sin/) for a good introductory explanation and see [Matt Gutting's answer](https://christianity.stackexchange.com/a/34320/10672) for other scriptural support. For preliminary research: - I found a good exposition of Patristic view of venial vs. mortal sin including many citations from St. Augustine, which Protestants hold in high esteem: [Why John Calvin did not Recognize the Distinction Between Mortal and Venial Sin](https://www.calledtocommunion.com/2011/11/why-john-calvin-did-not-recognize-the-distinction-between-mortal-and-venial-sin/) . The same article proposes an explanation of why John Calvin broke with the 1,000+ year long tradition. - Please note, that in the Catholic tradition, 1 John 5's "sin that leads to death" (forgivable through the sacrament of penance) is *different* than "unforgivable sin". Therefore, I would be very interested in how the reformers (Calvin, Luther, John Wesley) changed the interpretation of the relevant verses. - Based on Lesley's preliminary answer and other answers on this site (such as [this](https://christianity.stackexchange.com/questions/41863/how-do-protestants-understand-the-unforgivable-sin?rq=1)) it seems that Protestant traditions either conflates 1 John's "sin leading to death" with Matt 22:31's "unforgivable sin" or avoids the issue altogether. If so, a good Protestant answer should provide good exegetical grounds for equating "sin that leads to death" with "unforgivable sin", or else the answer should explain what John meant in the letter (like what Catholics do). **My question is**: In contrast with the Catholic tradition, how do various Protestant traditions (Reformed, Lutheran, and Methodist) take this distinction and apply it to the life of believers?