"We don’t know his faith background, e.g., if he was ever baptized in the past or if this was his first time meeting Jesus. His prayer “Jesus remember me when you come into your kingdom” shows he had some knowledge of the Gospel, since no such “kingdom” details are given in this passage."
There is a possibility that the repentant thief on the cross was either baptized or unbaptized. All that we can really do on this matter is speculate. Although the importance of baptism cannot be minimized, the grace and forgiveness of God is not restricted to this ritual.
By the way, a lot of the folks who say that the criminal did not need to be baptized due to being under the Old Covenant would simultaneously argue that Nicodemus needed baptism in order to be justified (John 3:5), who was also under the Old Covenant. That is a glaring logical inconsistency.
"Terms such as ‘faith’ and ‘belief’ are not used in this passage, so there’s no reason to think ‘faith alone’ is even the focus, just as the Parable of the Pharisee & Tax Collector (Lk 18:9-14) doesn’t use such terms, but rather highlights the virtue of “humility”.
So what good works did the thief on the cross do for salvation? While he did have a penitent heart, all that we see from the text of Scripture is him placing his trust in the Lord Jesus Christ. Humility is not a work, but a state of heart.
As for the Parable of the Pharisee and the Tax Collector, Christ was clearly addressing self-righteous individuals. The tax collector humbly believed on God for salvation, whereas the Pharisee relied on his own efforts to please Him. The first went home justified, whereas the latter was not. This parable is obviously about justification and the forgiveness of God.
"In fact, we see a range of virtues being expressed here, including ‘Fear of the Lord’ (23:40; cf Prov 1:7), Repentance (which Jesus distinguishes from belief, see Mark 1:5), Warning Sinners (2 Thess 3:14b), Public Professing (John 10:42; Rom 10:10b), as well as Hope of going to Heaven and certainly Love for Jesus. The thief was even willing to suffer and die for his own sins, not to be freed from them, which means he carried his own cross (Lk 9:23). So this was *far from* faith alone."
God has not prescribed the various things listed by the author as being requirements for justification. The exception would be repentance (which is not a work, but a change in heart), for how can a person be saved if he or she does not recognize the need of a Savior? Things such as fear of the Lord take place as a result of our hearts having been changed. These things are inextricably associated with justification. Our obedience should stem forth from a love of God and gratitude for the atonement that He has made on our behalf. It appears that the author is attacking some sort of a watered-down concept of faith.
"This was a unique situation, it isn’t the norm for how people typically accept the Gospel (see Acts for the norm), and as such it has its limits. For example, Jesus had not yet Resurrected, Ascended, or sent the Holy Spirit yet, so Dismas probably didn’t profess faith in these, whereas these aspects of Jesus’ mission are required for us to profess (Rom 10:9b). Even the command to “baptize all nations” wasn’t even given until *after* Jesus resurrected (Matt 28:19), so pointing to this as an example of ‘not needing baptism’ is kind of moot."
The "norm" that we observe in the New Testament is people believing on the gospel before getting baptized. The fact that the thief on the cross may not have known of the resurrection or the Great Commission is beside the point. If we are capable of adding our own works to the sacrifice of Christ, then He must have died in vain (Galatians 2:16-21).
"Plus, can we take this one example as an excuse to ‘not really have to’ obey the many teachings of Jesus and the Apostles, including getting baptized, gathering to worship with others, being subject to your pastor, sharing our possessions, etc?"
Talk about a classic example of a straw man fallacy! If a person gets saved, then his or her heart will be transformed through the power of the Holy Spirit.