Trichotomy is not a recent belief, neither is it merely "Pentecostal". It didn't originate with Jesse Penn-Lewis and much of what has been written on dichotomy has been unfair scholarship. JMO after much viewing of this debate over the yrs.
Trichotomous viewpoint -
"While the most of modern theology is Dichotomous, most of the early church and all of the Eastern church was Trichotomous. In the time of Christ all the Jews were Trichotomous Josephus 1:1,2. So was Justin Martyr, Tertulian, Origin, John of Damascus, Tatian, Clement Alexandrinus. In fact, no writing of the earliest church Fathers contains any idea of Dichotomy. Strong, in his systematic theology even quotes from some evolutionists to prove his dichotomy. P. 486, Leslie Olshausen well says on I Thess. 5:23, quoted in Smith's Bible Dictionary, p. 9l5--"It is indispensable, under a purely historical view, to acknowledge the triple division of human nature as a doctrine of the Apostolic age (and in agreement with our own belief)." "
G. H. Pember:
"Now the body we may term the sense-consciousness, the soul the self-consciousness, and the spirit the God-consciousness. For the body gives us the five senses; the soul comprises the intellect which aids us in the present state of existence, and the emotions which proceed from the senses; while the spirit is our noblest part, which came directly from God, and by which alone we are able to apprehend and worship Him."
L. S. Chafer in his Systematic Theology:
". . . many have assumed that the Bible teaches only a dichotomy. Over against this is the truth that oftentimes these terms cannot be used interchangeably. At this point it may be observed that there is the closest relation between the human spirit and the Holy Spirit--so close, indeed, that it is not always certain to which a referenceis made in the sacred text. . . The Holy Spirit works in and through the human spirit, but this is not said of the human soul. "The Spirit itself beareth witness with our spirit." (Rom 8:16).
Franz Delitzsch in his A System of Biblical Psychology:
"The psuche must be more than the form of existence, the individualization of the spirit; for Scripture certainly appropriates to the spirit and soul different functions, and often in juxtaposition. They must be distinguished even otherwise [more than by mere function]. . . A man would then not be able to speak of his spirit specially, and of his soul specially."
"And as for the essential condition of man, I certainly agree entirely with the view that the spirit and soul of man are distinguished as primary and secondary, but not with the view that spirit and soul are substantially one and the same."
Jamieson, Fausset, and Brown's commentary on 1 Thes 5:23
"All three, spirit, soul, and body, each in its due place, constitute man 'entire.' The 'spirit' links man with the higher intelligences of heaven, and is that highest part of man which is receptive to the quickening Holy Spirit (1 Cor 15:47). In the unspiritual, the spirit is so sunk under the lower animal soul . . . that such are termed 'animal' (E. V. "sensual, having merely the body of organized matter, and the soul the immaterial animating essence), not having the Spirit."
Fausset's Bible Dictionary: Spirit
Hebrew ruach, Greek pneuma. Man in his normal integrity ("whole," holokleeron, complete in all its parts, 1Th_5:23) consists of "spirit, soul, and body." The spirit links man with higher intelligences, and is that highest part receptive of the quickening Holy Spirit (1Co_15:47). The soul (Hebrew nephesh, Greek psuchee) is intermediate between body and spirit; it is the sphere of the will and affections.
In the unspiritual, the spirit is so sunk under the animal soul (which it ought to keep under) that such are "animal" ("seasonal," having merely the body of organized matter and the soul, the immaterial animating essence), "having not the spirit" (Jud_1:19; Jam_3:15; 1Co_2:14; 1Co_15:44-48; Joh_3:6). The unbeliever shall rise with an animal (soul-animated) body, but not, like the believer, with a spiritual (spirit-endued) body like Christ's (Rom_8:11).
The soul is the seat of the appetites, the desires, the will; hunger, thirst, sorrow, joy; love, hope, fear, etc.; so that nephesh is the man himself, and is used for person, self, creature, any: a virtual contradiction of materialism, implying that the unseen soul rather than the seen body is the man. "Man was made" not a living body but "a living soul." "The blood, the life," links together body and soul (Lev_17:11).
Lenski:
"Where, as here, [Heb 4:12] spirit and soul are distinguished, the spirit designates our immaterial part as it is related to God, as being capable of receiving the operations of the Spirit of God . . . The spirit ought to rule supreme; wholly controlled by God's Spirit, man ought to be pneumatikos . Sin enabled the psuche to control so that man became psuchikos , his bodily appetites having sway."
Richard Trench:
"The psuchikos of Scripture is one for whom the psuche is the highest motive power of life and action; in whom the pneuma , as the organ of the divine Pneuma , is suppressed, dormant, . . . whom the operations of this divine Spirit have never lifted into the regions of spiritual things. (Rom 7:14; 8:1; Jude 19)."
Oswald Chambers' lectures on biblical psychology:
"The spirit is the essential foundation of man; the soul his peculiar essential form; the body his essential manifestation."
"Remember, the whole meaning of the soul is to express the spirit, and the struggle of the spirit is to get itself expressed in the soul."
"God knows of no divorce whatsoever between the three aspects of the human nature, spirit, soul, and body; they must be at one, and they are at one either in damnation or in salvation."
Others trichotomists - T. Austin-Sparks, Herbert Lockyer, and Andrew Murray
http://www.ecbragg.net/Class%20Notes/Anthrop%20Sup%20I.htm
http://www.gracenotebook.com/pub/87.html