Questions about soul

1. In Mormon theology, spirits exist eternally—before, during, and after mortal life. Usually we refer to a "soul" as the combination of one's spirit and one's body. So souls do not exist before birth, but spirits do.

And after resurrection, our spirits are attached to our new, resurrected, incorruptible bodies.

• Alma 11:43 The spirit and the body shall be reunited in its perfect form. . .

Now, in regard to conscience and memory:

2. In Mormon doctrine, conscience is knowledge of right, often instilled/ inspired by the Holy Spirit. So it exists in the mind, but is not a product of the mind.

We also believe that memory, as well as attitudes, persist after death, and that each person will have a complete remembrance of their unrepented sins, at the Judgment.

• Alma 11:43 (continued) . . . and we shall be brought to stand before God, knowing even as we know now, and have a bright recollection of all our guilt.

2a) However, God has promised that as we repent of our sins, accepting the redemption of Jesus' sacrifice, even He will not remember those sins.

• Doctrine and Covenants 88:15

And he that has repented of his sins, the same is forgiven, and I, the Lord, remember them no more.

Orthodox Christianity does not believe in the preexistence of souls. Which means souls do have a beginning, and we all have a unique soul. We are made up of soul, mind, and body - the soul is what goes on into eternity if we follow God.

As far as I understand it, after we die we will still have our consciousness until after the final judgement. This means we have the ability even after death to decide to repent or not, until the day of Judgement comes. This is why we pray for the departed for God's mercy.

The term soul is translated somewhat confusingly, sometimes interchangeable with spirit and other times with mind.
There are too numerous verses and passages to discuss at length here, but the general concept taught is that a person has a physical body, what philosophers call a rational mind( sometimes translated as soul ), and a piece which is in regard to this world immaterial (spirit also sometimes translated as soul).

God is the generative force for all three (John 1:3 and Acts 17:28). To reject God, the generator, is by definition to degenerate. Therefore, in a sinful world all three can experience some kind of decay. God can restore all three.

Body:

2 Corinthians 4:16 [Full Chapter] Therefore, we are not discouraged; rather, although our outer self is wasting away, our inner self is being renewed day by day.

Matthew 10:28, "Do not be afraid of those who kill the body but cannot kill the soul.'

Mind:

Daniel 4-Nebuchadnezzar’s Madness. His rational mind is lost and restored.

Titus 1:15:"In fact, both their minds and consciences are corrupted."

Spirit:

1 Thessalonians 5:23 May God himself, the God of peace, sanctify you through and through. May your whole spirit, soul and body be kept blameless at the coming of our Lord Jesus Christ.

Revelation 3:1, Revelation 2:11 As physical death is the penultimate form of physical decay, so also there is mentioned a spiritual death/decay.

God provides salvation from this decay/death John 3, Ephesians 2

The architecture and relationship of these 3 things is an incredibly detailed discussion and there is a variance of interpretations. However your typical Protestant and Catholic will believe that all 3 have a definitive beginning caused by God (though they might not all three be created at the same time) and that the spirit then exists forever (though some might hold like the Jehovah's Witness that wicked spirits cease to exist rather than spend an eternity in hell).