The Catechism sections for today discuss the unity of human body and soul. Supplemental material comes from St. Gregory Thaumaturgus’ “On the Soul”.

II. "BODY AND SOUL BUT TRULY ONE"

362 The human person, created in the image of God, is a being at once corporeal and spiritual. The biblical account expresses this reality in symbolic language when it affirms that "then the LORD God formed man of dust from the ground, and breathed into his nostrils the breath of life; and man became a living being."229 Man, whole and entire, is therefore willed by God.

363 In Sacred Scripture the term "soul" often refers to human life or the entire human person.230 But "soul" also refers to the innermost aspect of man, that which is of greatest value in him,231 that by which he is most especially in God's image: "soul" signifies the spiritual principle in man.

364 The human body shares in the dignity of "the image of God": it is a human body precisely because it is animated by a spiritual soul, and it is the whole human person that is intended to become, in the body of Christ, a temple of the Spirit:232

Man, though made of body and soul, is a unity. Through his very bodily condition he sums up in himself the elements of the material world. Through him they are thus brought to their highest perfection and can raise their voice in praise freely given to the Creator. For this reason man may not despise his bodily life. Rather he is obliged to regard his body as good and to hold it in honor since God has created it and will raise it up on the last day 233

365 The unity of soul and body is so profound that one has to consider the soul to be the "form" of the body:234 i.e., it is because of its spiritual soul that the body made of matter becomes a living, human body; spirit and matter, in man, are not two natures united, but rather their union forms a single nature.

366 The Church teaches that every spiritual soul is created immediately by God - it is not "produced" by the parents - and also that it is immortal: it does not perish when it separates from the body at death, and it will be reunited with the body at the final Resurrection.235

367 Sometimes the soul is distinguished from the spirit: St. Paul for instance prays that God may sanctify his people "wholly", with "spirit and soul and body" kept sound and blameless at the Lord's coming.236 The Church teaches that this distinction does not introduce a duality into the soul.237 "Spirit" signifies that from creation man is ordered to a supernatural end and that his soul can gratuitously be raised beyond all it deserves to communion with God.238

368 The spiritual tradition of the Church also emphasizes the heart, in the biblical sense of the depths of one's being, where the person decides for or against God.239

IN BRIEF

382 "Man, though made of body and soul, is a unity" (GS 14 # 1). the doctrine of the faith affirms that the spiritual and immortal soul is created immediately by God.

St. Gregory Thaumaturgus’ treatise, “On the Soul” has an excellent discussion of the immortality of the soul:

6. Whether Our Soul is Immortal

It follows, in my opinion, as a necessary consequence, that what is simple is immortal. And as to how that follows, hear my explanation: Nothing that exists is its own corrupter, else it could never have had any thorough consistency, even from the beginning. For things that are subject to corruption are corrupted by contraries: wherefore everything that is corrupted is subject to dissolution; and what is subject to dissolution is compound; and what is compound is of many parts; and what is made up of parts manifestly is made up of diverse parts; and the diverse is not the identical: consequently the soul, being simple, and not being made up of diverse parts, but being uncompound and indissoluble, must be, in virtue of that, incorruptible and immortal.

Besides, everything that is put in action by something else, and does not possess the principle of life in itself, but gets it from that which puts it in action, endures just so long as it is held by the power that operates in it; and whenever the operative power ceases, that also comes to a stand which has its capacity of action from it. But the soul, being self-acting, has no cessation of its being. For it follows, that what is self-acting is ever-acting; and what is ever-acting is unceasing; and what is unceasing is without end; and what is without end is incorruptible; and what is incorruptible is immortal. Consequently, if the soul is self-acting, as has been shown above, it follows that it is incorruptible and immortal, in accordance with the mode of reasoning already expressed.

And further, everything that is not corrupted by the evil proper to itself, is incorruptible; and the evil is opposed to the good, and is consequently its corrupter. For the evil of the body is nothing else than suffering, and disease, and death; just as, on the other hand, its excellency is beauty, life, health, and vigour. If, therefore, the soul is not corrupted by the evil proper to itself, and the evil of the soul is cowardice, intemperance, envy, and the like, and all these things do not despoil it of its powers of life and action, it follows that it is immortal.

Footnotes

229 ⇒ Gen 2:7.
230 Cf. ⇒ Mt 16:25-26; ⇒ Jn 15:13; ⇒ Acts 2:41
231 Cf. ⇒ Mt 10:28; ⇒ 26:38; ⇒ Jn 12:27; ⇒ 2 Macc 6 30.
232 Cf. ⇒ I Cor 6:19-20; ⇒ 15:44-45.
233 GS 14 # 1; cf. ⇒ Dan 3:57-80.
234 Cf. Council of Vienne (1312): DS 902.
235 Cf. Pius XII, Humani generis: DS 3896; Paul VI, CPC # 8; Lateran Council V (1513): DS 1440.
236 1 Th 5:23.
237 Cf. Council of Constantinople IV (870): DS 657.
238 Cf. Vatican Council I, Dei Filius: DS 3005; GS 22 # 5; Humani generis: DS 3891.
239 Cf. ⇒ Jer 31:33; Dt 6:5; 29:3; ⇒ Is 29:13; ⇒ Ezek 36:26; ⇒ Mt 6:21; ⇒ Lk 8:15; ⇒ Rom 5:5.