The nature of salvation
Salvation is by grace apart from works by faith alone. Good works are the result, not the cause, of salvation (Eph 2:8-10).
Since we continue to sin after being saved (1 Jn 2:1,2), a complete commitment is not a prerequisite of salvation. But MacArthur argues that a complete commitment is a prerequisite (p. 134), even though he qualifies this demand for submission and obedience as a "willingness to obey" (p. 88).
MacArthur says that while "eternal life is indeed a free gift. . .that does not mean there is no cost in terms of salvation's impact on the sinner's life. This paradox may be difficult but it is nevertheless true: salvation is both free and costly. . .It (saving faith) is an exchange of all that we are for all that Christ is. And it denotes implicit obedience, full surrender to the lordship of Christ. Nothing less can qualify as saving faith" (p. 140). "This is the kind of totally committed response the Lord Jesus called for. A desire to follow him at any cost. Absolute surrender. A full exchange of self for the Savior. It is the only response that will open the gates of the kingdom" (p. 141). This double-talk. If salvation is free, it costs us nothing; if it is costly to us, then it is not free. He takes certain positional changes that occur when we receive salvation (co-crucifixion) and implies that they are conditional attitudes that are necessary.
What constitutes saving faith
Saving faith is essentially resting upon the truth of God's Word and specifically upon Christ and his satisfaction of God's wrath by his atoning death. Thus, it involves being aware of this promise (notitia), assenting to its truthfulness (assensus) and sincerely, personally trusting it (fiducia). Mental assent without personal trust falls short of biblical faith (Titus 1:16; Jas. 2:19; Jn. 1:12).
Saving faith differs in degree in those who possess it. Thus, the Bible speaks of true Christians who are weak in faith (Rom. 14; 1 Cor. 8), and of the need to grow stronger in faith (Rom. 4:19,20). Thus, while we are always to be headed toward a more perfect faith, we never achieve it in this life.
The position that "If he is not Lord of all, he is not Lord at all" is unbiblical. Jesus is both Savior and Lord, but no Christian ever perfectly submits to his lordship at all times. Since this slogan needs to be continually modified, what use is it?
MacArthur says that saving faith "retains no privileges. It clings to no cherished sins, no treasured possessions, no secret self-indulgences. It is unconditional surrender, a willingness to do anything the Lord demands. (pp. 139,140)" This is absolutely ridiculous. He is making the pinnacle of spiritual maturity the requirement for salvation. We must attain to a perfect attitude of submission before we can be forgiven.
The nature of repentance
Biblical repentance is simply the negative aspect of its positive compliment - faith in Christ as Savior. Repentance must occur for salvation, because one must change his mind about Jesus and his need for forgiveness in order to trust Christ for salvation.
The relationship of saving faith to sanctification
Sanctification is a gradual process and it is imperfect in this life. It is possible for true Christians to allow the flesh to dominate their lives so that the distinctive fruit of the Spirit is absent (1 Cor. 3:2,3), even though God will discipline them for this (1 Cor. 11:30-32; Heb. 12:5-8).
The desire to change comes from the Holy Spirit in the regenerate person (Phil 2:13). Therefore, to demand from a person a "complete change of heart, attitude, interest, and direction" (p. 32) is to make regenerate behavior from an unregenerate person the requirement for regeneration!!
Mercy and lordship
We must confess the lordship of Christ to be saved (Rom 10:9,10). This means that we must acknowledge Jesus as God and the sole bestower of salvation and that he has the implicit right to rule us.
This confession must must personally sincere, not mere mental assent profession.
Salvation is received by faith alone; repentance should be understood as part of faith.
The realization of the extent of Christ's lordship in growing obedience to his will is the work of sanctification, not justification.
It is possible for true Christians to be carnal, though this state is not normative (because God disciplines it) or permanent.
To insist on complete submission to God's will as necessary for salvation is unsupported by the New Testament.
It is sounder and simpler to keep to Paul's invitation to the Philippian jailer Acts 16:31 - "Believe in the Lord Jesus and you shall be saved."
While lack of growth in the church is not corrected by shallow professions from "decisional evangelism" campaigns, carnality in the church is not corrected by introducing sterner demands that have problematic biblical support.
How we communicate the gospel to others.
We should be clear that genuine willingness to bow to Christ and humbly receive forgiveness is stressed, but just as clear that salvation is a free gift, and that you may come as you are without any actual ethical change preceding your decision.
How we assure new Christians.
We should stress what the Bible says about their new standing in Christ as foundational because this is objective and unchanging. Experiential changes (conviction of sin, deliverance from sin, etc.) are important but should be subordinate because they are subjective and fluctuating.
How we discern the validity of professions of faith.
We may wonder if someone has only mental assent, and we may ask them how they know they are saved. But if the person is able to articulate why they are saved, we should stop short of asserting they are not saved, and instead urge them to walk with Christ and grow spiritually.
 S. Lewis. Johnson, "How Faith Works," Christianity Today, Septenber 22, 1989, pp. 21-25
 John F. MacArthur, The Gospel According To Jesus (Grand Rapids: Zondervan, 1988)