According to Catholicism, Can God annihilate the soul?

Jesus makes it very clear in making known in Rev 14 that in the smoke of their torment will ascend for ever and ever in the presence of the holy angels and Himself.

Furthermore, according to Isaiah 6:24, He will allow His people to visit/view the eternal fire, after He creates the new heaven and new earth, All flesh come to worship before me, saith the Lord.

24 And they shall go forth, and look upon the carcasses of the men that have transgressed against Me: for their worm shall not die, neither shall their fire be quenched; and they shall be an abhorring unto all flesh.

This indicates that their worm – eternal soul never ceases existence.

The devil (once a beautiful Holy angel) attempted to take over God, His creation and corrupted mankind in the process. God will ensure that those that went against Him (and His Word) , will reap the eternal destruction. You are either for Him, or against Him, regardless what anyone on the internet claims. Jesus said it Himself, through His Word.

Matthew 12:30 (NKJV) 30 He who is not with Me is against Me, and he who does not gather with Me scatters abroad.

This is the way it is, become entrenched in Him and His Sprit, live according to His Word regardless what today’s society claims or thinks. Seek Him and He will enlighten you through His Word, He will give you the Peace that passes all understanding. You will be amazed and gain understanding. He will put your mind to rest.

Opening

Making a distinction between a mortal thing and to annihilate something.

With the former, a mortal thing can be killed, made to die, die, with the latter, an annihilated thing is reduced to nothing.

From a Catholic perspective, to create means to call [a being] into existence out of nothing.

CCC IN BRIEF 318 No creature has the infinite power necessary to "create" in the proper sense of the word, that is, to produce and give being to that which had in no way possessed it (to call into existence "out of nothing") (cf DS 3624).

Thus the reverse action, the opposite of create is annihilate and not kill/make to die.

Answering

ALL creation, the human soul included, depends on God for its conservation or continuance in being.¹

CCC IN BRIEF 320 God created the universe and keeps it in existence by his Word, the Son "upholding the universe by his word of power" (Heb 1:3), and by his Creator Spirit, the giver of life.

Thus from Catholic teaching and Sacred Scripture, ALL creation, the human soul included, would go back to the nothingness from which it was called if God so wished and withdrew his upholding power.

^{1. cf. God upholds and sustains creation, CCC 301 and Relation of God to the Universe | New Advent.}

The soul, as the OP pointed out, is immortal, and made so from the very first moment of its existence when created by God. Thus the immortality of the soul is a natural property of the soul in the image of its Creator, again as correctly stated by the OP.

What is the answer if the OP's question is understood as, [I]f God created the soul immortal, can God kill it?

This is would be a classic contradiction and better dealt with by philosophers. The argument against this scripturally would be:

Nm 23:19 (RSVCE) God is not man, that he should lie, or a son of man, that he should repent. Has he said, and will he not do it? Or has he spoken, and will he not fulfil it?

Addressing the OP's difficulty that led to the question

Will souls - accurately the whole person, body and soul - be tormented forever or be annihilated?

I am not sure I can present another answer if this one does not suffice.

If God so loved the world that he gave his only Son, that whoever believes in him should not perish but have eternal life, then the reasoning is faulty that projects God 'as unfair, mean, sadistic, to torture' souls forever in hell.

Quite frankly, the inspiration behind those wanting personal annihilation should they of their own volition fail to attain eternal life, is the same inspiration, barring illness, that's behind suicide. Akin to 'taking the ball and going home'.

What about the second death that scripture speaks about?

The linked passage above equates that to [being thrown into] 'the lake of fire' and 'one's name not being written in the book of life' i.e. not having 'eternal life'.

While angels and human souls - rational spiritual beings - have a natural immortality, God called them - angels and men - and willed that they, cooperating with him, would attain to supernatural eternal life, i.e. share in his own life, drawing from it. The absence of this life is the second and eternal death.

Further reading:

• Soul | New Advent.
• Immortality | New Advent.

In the Summa Theologica (First Part, Question 104, Article 3), Aquinas asks "Whether God can annihilate anything?" He concludes,

Some have held that God, in giving existence to creatures, acted from natural necessity. Were this true, God could not annihilate anything, since His nature cannot change. But, as we have said above, such an opinion is entirely false, and absolutely contrary to the Catholic faith, which confesses that God created things of His own free-will, according to Ps. 134:6¹: "Whatsoever the Lord pleased, He hath done." Therefore that God gives existence to a creature depends on His will; nor does He preserve things in existence otherwise than by continually pouring out existence into them, as we have said. Therefore, just as before things existed, God was free not to give them existence, and not to make them; so after they are made, He is free not to continue their existence; and thus they would cease to exist; and this would be to annihilate them.

In other words, Aquinas believes that since God creates things because he wants to, and because he loves them, we must believe that it was possible for him not to give things (including the soul) existence, and similarly at least theoretically possible for God to fail to continue them in existence.

However, the very next question he considers is "Whether anything is annihilated?" (emphasis added) His conclusion is:

Some of those things which God does in creatures occur in accordance with the natural course of things; others happen miraculously, and not in accordance with the natural order, as will be explained. Now whatever God wills to do according to the natural order of things may be observed from their nature; but those things which occur miraculously, are ordered for the manifestation of grace, according to the Apostle, "To each one is given the manifestation of the Spirit, unto profit" (1 Cor. 12:7); and subsequently he mentions, among others, the working of miracles.

Now the nature of creatures shows that none of them is annihilated. For, either they are immaterial, and therefore have no potentiality to non-existence; or they are material, and then they continue to exist, at least in matter, which is incorruptible, since it is the subject of generation and corruption.² Moreover, the annihilation of things does not pertain to the manifestation of grace; since rather the power and goodness of God are manifested by the preservation of things in existence. Wherefore we must conclude by denying absolutely that anything at all will be annihilated.

In other words:

• If God annihilates something, he will do it either (a) as part of the natural course of things, or else (b) as a miracle, to display his power or for some other teaching purpose.
• But in nature, we see that no created entity is annihilated in the natural course of things. Either they are material, and the matter constituting them continues in existence even after they die or are worn down to nothing; or else they are immaterial, in which case (since they are pure form with no accident) it is impossible for them to fail to exist.
• Furthermore the annihilation of entities does not constitute a display of God's grace and power; these are best displayed by God's maintaining things in existence:

For you love all things that are
and loathe nothing that you have made;
for you would not fashion what you hate.
How could a thing remain, unless you willed it;
or be preserved, had it not been called forth by you?
But you spare all things, because they are yours,
O Ruler and Lover of souls,
for your imperishable spirit is in all things!

(Wisdom 11:24–12:1)

Thus, since God does not annihilate anything either in the natural course of events or as a miracle, we must believe that nothing at all—including the soul—is ever in fact annihilated.

¹ Psalm 134 in the Septuagint, 135 in the Hebrew numbering.

² That is, Thomas claims, because beings are generated out of matter, and they degenerate and decay (they are corrupted) back into matter, the matter itself is not corruptible. Matter can be formed into new entities, and these entities can decay back into matter, but the matter itself is not created nor destroyed—it is not corruptible.