This is the summary of the 3rd part of the book, which I think is most important.
The distinguishing signs of true spiritual emotions:
1) True spiritual emotions arise from spiritual, supernatural and divine influences of the heart.
Spiritual -> not referring to the intangible aspect of human, eg feelings, but referring to the Holy Spirit. (Proof: Col 2:18 says such 'spiritual' aspect of human beings can indeed be false)
The Spirit of God can and does influence natural men (Numbers 24:2, 1 Sam 10:10, Hebrews 6:4-6)
Imagination and delusions, however, can produce natural, not spiritual emotions.
2) The object of spiritual emotion is the loveliness of spiritual things, not our self-interest.
The relation is not exclusive (Psalm 116:1), but self interest is made secondary.
Nothing can be spiritual if it is the result of self-love (Luke 6:32). Self-love can produce, however, gratitude, love of God with a lack of conviction of sin, or loving God because God blesses us.
Real Christians do not first see that God loves them, and later find out that He is lovely, but find out that He is lovely first, and their love for God arises from this view. True love begins with God and loves Him for His own sake.
It is true that God first loved us, and we can't escape that. With this, we love God not because that fact that 'He loved us', but because of His moral perfection.
3) Spiritual emotions are based on the moral excellence of spiritual things.
Moral excellence is not talking about the outward performance of duties, but mainly concerned upon holiness, the sum total of truth, righteousness, goodness. Power, knowledge and eternity are good, but they are not beautiful apart from holiness. So love of God must begin with delight in His holiness. It is from God's holiness that the rest of His being derives its beauty.
4) Spiritual emotions arise from spiritual understanding
Spiritual knowledge is not doctrinal knowledge. Doctrinal knowledge involves mere intellect. Spiritual knowledge is a sense of the heart in which we see the beauty of holiness in Christian doctrines. It involves the intellect and the heart. (1 Cor 13:2)
It would not be Spiritual knowledge if God immediately revealed His will to our minds by the Holy Spirit, as it would be doctrinal, not spiritual.
Next, Spiritual understanding sees what is actually in Scripture and not make a new meaning for it. Eg. when some words relating to Scripture enters someone's head.
Lastly, imaginary ideas can arise out of spiritual emotions, but spiritual emotions cannot arise out of imaginary ideas.
5) Spiritual emotions bring a conviction of the reality of divine things.
Many religious experiences are just moving, and not convincing. They produce no lasting change as they are not grounded in a settled and indisputable conviction of the realities described by the truth of the Gospel.
Emotions arising from a strong conviction may not also be spiritual if this conviction is unreasonable (founded by real evidence and good reasons, not upbringing alone).
Rational arguments might also just convince the person intellectually without saving the person, eg Simon the magician (Acts 8:13)
Conviction of truth of the gospel arises out of the sense of its divine beauty, not mentioning that historical evidence and other arguments are useless.
6) Spiritual emotions always exist alongside spiritual humiliation.
It is the sense of how insufficient and detestable we are as Christians. Unbelievers have legal humiliation, but they do not see the hateful nature of sin, or renounce sin in their hearts, or surrender themselves to God. They feel humbled by force, but no humility.
Spiritual humiliation is the essence of Christian self-denial. First, deny his worldly inclinations, and second, deny his self-righteousness and self-centredness.
Spiritual pride can disguise itself as humility, but two signs distinguishes: 1) The proud compares himself with others and has a superior opinion on themselves. 2) The proud man tends to think very highly of his humility, while the humble man thinks of himself as very proud.
7) Spiritual emotion always exist alongside a change of nature.
The transforming power comes only from God - the Spirit of the Lord (2 Cor 3:18)
If there is no real and lasting change in people who think they are converted, their religion is worthless whatever their experiences may be.
Conversion does not destroy natural temperaments that made us prone to certain sins, but these temperaments will not dominate his soul and his life as they did before. Sincere repentance will make a person particularly hate and fear the sins of which he used to be most guilty.
8) True spiritual emotions differ from false ones, in promoting a Christlike spirit of love, humility, peace, forgiveness and compassion.
Holiness in all its aspects belong to Christian character, but there are certain aspects which deserve the name of 'Christian' in a special degree, as they reflected the divine attributes of God and Christ particularly in redeeming sinnesrs, eg humility, gentleness, love, forgiveness and mercy.
Christian courage is often misunderstood. It is not brutal fierceness but 1) ruling and suppressing the evil emotions of the mind 2) resolutely following and acting on the mind's good emotions, without being hindered by sinful fear or hostility of the enemies.
There is a false boldness for Christ which arises from pride.
In the true Christian, however, it is not meant that there is nothing contrary to the above characters, for we are not sinlessly perfect, though it will have the tendency to promote the spirit.
9) True spiritual emotions soften the heart, and exist alongside a Christian tenderness of spirit.
False emotions may seem to melt the heart for a time, but in the end they harden it, because they have such a high opinion of themselves. True spiritual emotions make the heart tender, like bruised flesh which is easily hurt.
10) True spiritual emotions, unlike false ones, have a beautiful symmetry and balance.
The symmetry of the Christian's virtues is not perfect, but they never display that grosteque lack of balance which marks the religion of hypocrites.
A Christian's love must be universal. (Contrast with 1 John 4:20)
Some people show love to others in respect of their bodily needs but have no love for their souls. Others pretend a great love for men's souls but have no compassion for their bodies. (Contrast with Mark 6:33-44)
11) True spiritual emotions produce a longing for deeper holiness, but false emotions rest satisfied in them.
The more a true Christian loves God, the more he desires to love him, the more uneasy he is at his lack of love for Him.
12) A fruit of true spiritual emotions is Christian practice.
The true Christian seeks to conform every single area of his life to the rules of God's Word (John 15:14)
The true Christian makes holy living the main business of his life. (Titus 2:14, 2 Tim 2:3, 1 Tim 6:12, 1 Cor 9:24, Eph 6:13-17, Phil 3:13-14)
The true Christian perseveres in his obedience (Matt 13:3-9, 18-23). The genuine Christian keeps on believing and obeying despite the various problems he meets.
True Christians can grow spiritually cold, but never fall away till they get tired of God and obedience, and becomes settled in a dislike of Christianity.
13) Christian practice is the chief sign to others of a convert's sincerity.
'You will know them by their fruits' (Matt 7:16)
'What does it profit, my brethren, if someone says he has faith but does not have works?' (James 2:14)
No outward appearances, are however, infallible signs of conversion. But it is the best evidence. Yet, if we could see as much of a person's practice as that person's own conscience knows, it might be an infallible sign of his condition.
14) Christian practice is a sure sign of conversion to a person's own conscience.
'By this we know that we know him, if we keep his commandments' (1 John 2:3)
Other verses: (Gal 6:4, 1 John 3:18-19, Matt 6:21)
Obedience is properly the act of the sould, since the soul governs the body.
There are two ways that a Christian's soul can act : 1) purely inward way by meditating God's truth, that our minds rest in that truth and do not go beyond to some outward act. 2) practical way which results in outward bodily action.
Christian has to judge his own practice not just by what he does outwardly, but by the inward motives of his soul. (Rev 2:23 says that God searches the 'minds and hearts')