John Macarthur's false gospel is grounded in existential works

"The gospel Jesus proclaimed was a call to discipleship, a call to follow Him in submissive obedience, not just a plea to make a decision or pray a prayer. Jesus' message liberated people from the bondage of their sin while it confronted and condemned hypocrisy. It was an offer of eternal life and forgiveness for repentant sinners, but at the same time it was rebuke to outwardly religious people whose lives were devoid of true righteousness. It put sinners on notice that they must turn from sin and embrace God's righteousness. It was in every sense good news, yet it was anything but easy-believism." - John Macarthur, The Gospel According to Jesus, 37

The Bible teaches clearly that the evidence of God's work in a life is the inevitable fruit of transformed behavior (1 John 3:10). faith that does not result in righteous living is dead and cannot save (James 2:14-17). Professing Christians utterly lacking the fruit of true righteousness will find no biblical basis for assurance of salvation (1 John 2:4). - Pg. 39

Genuine assurance comes from seeing the Holy Spirit's transforming work in one's life, not from clinging to the memory of some experience. - Pg. 39

Macarthur says all of this. In the first paragraph he claims that the gospel proclamation is a call of discipleship. Keep in mind what he is saying is that the gospel calls us to do something. However, this is not at all what the gospel message is. The gospel message is made of indicative statements about what God has done in Christ Jesus on the cross for the elect's sin. It does not command us to do anything or call us to do anything.

The bible does not say that evidence of God's work in a life is basic transformed behavior. What it does say "In this the children of God are manifest, and the children of the devil: whosoever doeth not righteousness is not of God, neither he that loveth not his brother." - 1 John 3:10

Loving the brethren is not the only thing Christians do but they also love God and they love God by knowing about God and studying his word. As Christians who also love God and His truth we love one another through various circumstance. But to say that behavior is evidence of the Christian life is false.

But our assurance does not come from our own broken works. Assurance for the Christian comes not from what is in him nor comes from him but is completely external. The assurance of the Christian Is grounded in Christ's complete work on the cross where he alone has atoned for the sins of his elect alone so that there is therefore now no condemnation for those who are in Christ Jesus. Those who are conditionalist simply make salvation and assurance depend and kept on the good works of the sinner whether it is something that the sinner himself does or whether it is infused by grace.

Assurance is necessary for good works but assurance does not come from the sinners works. We are called to make our calling and election sure not by our good works.

Assurance comes by gaining understanding of God's truth - more specifically the Gospel not by looking at our transformed lives. For our works are not perfect.