The soul and the spirit are very closely related in the Bible (see 1 Samuel 1:15; Job 7:11; Isaiah 26:9), thought there is a difference (Hebrews 4:12). 1 Thessalonians speaks of use being preserved in body, soul, and spirit (1 Thessalonians 5:23). It is my opinion that the salvation of the soul and the salvation of the spirit is virtually synonymous.
You may be referring to the argument posed by Professor Zane Hodges (at least he was my professor in seminary) in his book, The Gospel Under Seige, chapter 3, entitled “What is Dead Faith?”, which is about James chapter 2. Personally I don’t find his argument compelling, but he seeks to argue that the salvation of the soul is the preservation of the earthly life. This is all wrapped up in the question James raises, “Can (that kind of) faith save him?”Professor Hodges’ article is discussed on the BSF Website) — James.