Yet we who are in Christ have been given a new heart and the helper, The Holy Spirit who guides us. Consider the parable of the tax collector and the Pharisee. The tax collector who was grieved by his sin was justified by God because he humbled himself to Him. It was his repentant heart that was the reason he was justified (declared righteous) by God not his perfection in obedience brother.
If Luke 18:9-14 was the only passage in the Bible, you might be onto something, brother; But it is not the whole counsel of God's Word. Yes, we are initially and foundationally saved by God's grace. No doubt about it. If a believer genuinely messes up and or sins, they can confess of their sins to the Lord Jesus Christ, and be forgiven of them, but if one's mindset is that they will always be a slave to mortal sin in this life, they are just paying lip service and they are merely toying with sin and serving two masters. It's still a form of justifying sin with this kind of thinking because it makes room for serious sin in our lives when the Lord condemns sin and requires us to cut off grievous sin and to live holy as a part of the Sanctification Process (After we are saved by His grace).
The problem with the Pharisee in the Parable in the Tax Collector was not that he was in any kind of Sanctification Process (because such a thing did not exist yet for the average believer until Pentecost), but the issue was that he was trying to be saved by “Works Alone” without God's grace. The Pharisee was not humbling himself first in seeking forgiveness with the Lord like the Tax Collector did. This was not because God's Word here is teaching that it is impossible for believers to overcome mortal sin and so we should just pay empty lip service. That would be silly, for Jesus Himself said to two people to “sin no more” (John 5:14) (John 8:11). In fact, the whole point of why God said I desire mercy and not sacrifice was in the fact that the Jews had offered sacrifices but their hearts were not right with God in that they justified sin. Yes, they would do certain commands by God that were outward like the sacrifices, but they needed to clean the inside of the cup (or the inside of their heart with truly being broke up about their sin with the Lord Jesus Christ). For 2 Corinthians 7:10 says “
For godly sorrow worketh repentance to salvation not to be repented of [i.e. not to be regretted]:” If you were to read 2 Corinthians 12, Paul says:
20 For I fear, lest, when I come, I shall not find you such as I would, and
that I shall be found unto you such as ye would not: lest
there be debates, envyings, wraths, strifes, backbitings, whisperings, swellings, tumults:
21 And lest, when I come again, my God will humble me among you, and
that I shall bewail many which have sinned already, and have not repented of the uncleanness and fornication and lasciviousness which they have committed.”
(2 Corinthians 12:20-21).
In other words, Paul was going to rebuke them greatly if they did not forsake their wicked ways.
