To believe means to agree that Jesus is the Son of God and to trust and follow what he says.
So paradoxically, you just have to believe, but you don't have to believe.
Because intelligent agreement presupposes trust.
…It is time to reaffirm that faith is not simply an intellectual assent, but an intellectual assent to believe that true salvation comes when Jesus Christ is the Son of God and is the Lord of our lives, and to trust Him completely.

--- p.20~21

Ultimately, it becomes a question of perspective whether faith is seen as an act of human obedience or an act of Christ's obedience.
However, the Bible calls the viewpoint of Christ's obedient actions 'faith.'
The statement, “You will be saved if you just believe” should not be understood to mean, “You will be saved if you just say you believe” or “You will be saved if you just admit that you believe.”
Rather, it should be taken to mean 'only through the obedience of Christ.'
This involves elements of both intellectual agreement and trust.
But what is clear is that the basis of our salvation is not the state of our hearts, but the obedience of Christ.
This is grace.
So, if you just believe, you will be saved.

--- p.26

Dead faith is not faith.
Moreover, James said that faith without works is dead (James 2:26).
Therefore, it was possible to make the logical leap that one cannot be saved without works, and that works are the means to salvation.
But James did not say, "How can we be saved?" but rather, "How can our faith be active?"
In other words, I am talking about a way to show that faith is alive.

--- p.45

They say they believe but have no faith.
The contrast is a little clearer in the English Bible.
“I believe; help my unbelief!” (ESV).
This is not a contradiction, but a paradox.
It doesn't mean that you have half and half faith, half and half disbelief, or that you believe and half and half but it refers to a state of tension where you believe completely but are still anxious and unsure.

--- p.65

The cry of the Father, “I believe; help my unbelief,” is not the cry of an unbeliever.
It is the cry of a person who tries to live by faith because he believes.
In the phrase “I clearly believe, so why am I so uneasy?” the word “clearly” is not a lie or hypocrisy.
Even the most sincere confessions can be unsettling.
It's like when you're sitting on a boat at sea, it's natural for the boat to rock back and forth with the waves, but when it rocks violently, you get anxious as if the boat might capsize (even if you're sure it won't).
Even though the confession of faith is a one-time event, it is only the beginning of the journey of faith.
Faith is a beginning, even if it is the most certain beginning and the outcome is very clear.
If we say that faith is the end, the time from the moment we begin to believe until the moment the Lord calls us can easily become a meaningless blank space.

--- p.68

It is not that human willful decision is an absolute condition without which even God cannot do anything, but rather that it is a condition required by God, who has already accomplished the work, to confirm the relationship and for the saints to enjoy within that relationship.
Therefore, the demand for faith is a demand for love.
In this sense, the command and demand to “believe” is actually a gift and a confirmation of the gift.
But at the same time, we cannot ignore or neglect God's call to "believe" and to make a decision of our own will.
Responding to the Lord's request with a sincere heart will bring joy to God and infinite blessing to us.
--- p.96

The phrase 'of little faith' means someone who is shaken by the waves in the situation at the time.
The phrase, “Did you doubt?” is not a rebuke, but rather a description of the state of mind at the time.
So, this does not mean that Peter originally had less faith than the other disciples, but rather that he wavered in that situation.
When we stand before tribulation, we are shaken dozens of times a day.
Even those who are courageous in the face of adversity may waver and lose their composure when faced with temptation.
That moment of sway is a state of little faith.
So, it is not that there are people with little faith, but rather that everyone experiences a state of little faith.

--- p.134~135

The phrase, “Believe and doubt nothing” does not mean to find peace of mind, but to not lose sight of God’s goodness in the midst of suffering.
A state of not having any doubts in the midst of suffering does not mean a peaceful (or indifferent) state with little feeling, but rather a state of holding on tightly to the good God.
The words, “Ask in faith, nothing wavering,” do not mean that we should believe that what we ask will be granted, but rather that we should not waver in our belief in God’s goodness and tell God about all our circumstances and situations.
--- p.151~152

Jesus is the one who has mercy on us, the one who can solve our problems, and the Messiah.
Jesus did not come to heal the sick, but to have mercy on us, free us from sin, and give us eternal life.
So the Lord showed that Christ is the Messiah through healing the sick.
Because the Lord had mercy on us.
But when Jesus healed the sick, faith was mentioned.
This faith is not the faith that leads to salvation.
This faith is a kind of confidence that Jesus can heal the sick.
Therefore, the Gospel does not see this faith as the faith that leads to salvation, but rather as the faith that begins to look to the Lord so that one can attain that faith.
With this belief, you may not be healed and may not be saved.
So, theologically, this faith is sometimes called ‘working faith’ to distinguish it from ‘saving faith.’

--- p.196

Vaguely hoping that God will make things work out for us is not the reality of what we hope for.
The reality of what we hope for is Jesus Christ, the proof of God's love who is with us without change, no matter what the circumstances.
We have already seen Christ come to this earth through the Word and through the inspiration of the Holy Spirit.
We have the substance of things hoped for, and have seen the evidence of things not seen.
So, we are united with Christ and are walking with Christ on this earth now.

--- p.243

The question, “What do Christians believe and what do they pursue?” was a truly serious one for Paul.
Because that is the essence of faith.
I believe that in order to understand what Paul is trying to say, we need to delve deeper into the "Christian identity" that Paul is ultimately concerned with.
Otherwise, this issue could devolve into a discourse of speculative religious practice.
This is a question that belongs to the essence of faith.
In other words, the essence of faith is that Christians are not simply people who go to heaven when they die, but people who live as sojourners on this earth precisely because of that hope.

--- p.282