We observe a few examples within the context of the TANAKH or the Old Testament. For example, we have Omri, the king of Israel in 1 Kings 16.
"21 Then the people of Israel were split into two factions; half supported Tibni son of Ginath for king, and the other half supported Omri. 22 But Omri’s followers proved stronger than those of Tibni son of Ginath. So Tibni died and Omri became king.
23 In the thirty-first year of Asa king of Judah, Omri became king of Israel, and he reigned twelve years, six of them in Tirzah. 24 He bought the hill of Samaria from Shemer for two talents[a] of silver and built a city on the hill, calling it Samaria, after Shemer, the name of the former owner of the hill.
25 But Omri did evil in the eyes of the Lord and sinned more than all those before him. 26 He followed completely the ways of Jeroboam son of Nebat, committing the same sin Jeroboam had caused Israel to commit, so that they aroused the anger of the Lord, the God of Israel, by their worthless idols.
27 As for the other events of Omri’s reign, what he did and the things he achieved, are they not written in the book of the annals of the kings of Israel? 28 Omri rested with his ancestors and was buried in Samaria. And Ahab his son succeeded him as king."
Omri accomplished many feats, including the building of the city and also was presumably a brilliant military tactician. But alas despite his feats, though they were recorded, he is dismissed for the fact that he did evil in the sight of the Lord.
The good works that a man does outside of Christ are filthy rags and we cannot merit our salvation via our good works.
"Isaiah 64:6 All of us have become like one who is unclean,
"Isaiah 64:6 All of us have become like one who is unclean,
and all our righteous acts are like filthy rags;
we all shrivel up like a leaf,
and like the wind our sins sweep us away.
7 No one calls on your name
or strives to lay hold of you;
for you have hidden your face from us
and have given us over to[b] our sins."
To drive his point home of how tainted our works are thanks to original sin, Isaiah in the Hebrew uses the illustration of a used menstrual cloth (a tampon in the modern era if you will). This is what our works are like in the sight of God, hence why no amount of good deeds before a holy god can merit our salvation. When a person comes to Christ through repentant faith, he is justified, and by the Holy Spirit, he is sanctified. Good works of a man are something that Christians do out of gratitude to Christ, not something to merit or earn their salvation. See my article on James 2:
Keith Thompson in his article on Justification by faith alone, notes the following:
"Now, the other argument is that since James 2:21 says Abraham was justified by works when he offered up Isaac on the alter in Genesis 22, this must mean Abraham was justified more than once in the same way in which Paul describes in Genesis 15:6. However, the problem with this argument is that James and Paul are talking about two different things. Paul is talking about Abraham being declared righteous or acquitted by faith apart from works based on righteousness being credited or imputed to Abraham’s account. This is not what James is talking about. As New Testament scholar Robert Reymond observes, “Whereas Paul intends by ‘justified’ the actual act on God’s part whereby he pardons and imputes righteousness to the ungodly, James intends by ‘justified’ the verdict which God declares when the actually (previously) justified man has demonstrated his actual righteous state by obedience and good works” (Robert Reymond, Paul: Missionary Theologian, [Christian Focus Publications, 2000], p. 442). To demonstrate the existence of this concept Reymond further notes, “That a distinction must be drawn between God’s actual act of justification whereby he pardons and constitutes the sinner righteous and his subsequent declaring act of justification whereby he openly acquits the justified sinner before others is verified by our Lord’s actions in connection with the woman who washed his feet in Luke 7:36-50. He openly declares to Simon the Pharisee and to the woman herself that her many sins were forgiven (vss 47-48) ‘because she loved much [ὅτι ἠγάπησεν πολύ]’ (47). But it is apparent that she had already been actually forgiven on some previous occasion because her acts of devotion toward him – the fruit and evidence of a lively faith – were due, he states, to her having already had ‘her debt cancelled’ (41-43). The chain of events then is as follows: On some previous occasion Jesus had forgiven her (her actualjustification). This provoked in her both love for him and acts of devotion toward him. This outward evidence of her justified state evoked from Christ his open declaration that she was forgiven (herdeclared justification)” (Robert Reymond, Paul: Missionary Theologian, [Christian Focus Publications, 2000], p. 442 n. 27). Indeed, James is teaching by doing works Abraham was declared to have already been justified by faith (James 2:23), that is his "declared justification," not that he was made right with God through works. Paul is clear that comes by faith apart from works so that no one can boast (Romans 4:2-8). James is affirming, then, works are the evidence of being declared righteous or justified by faith and they result in God openly declaring the person to be justified. Every true believer will exhibit these works, not because they merit right standing with God or contribute to actual acquittal, but because they are the evidence of justification, or the completion of faith (James 2:22)." (Keith Thompson, Justification is by Faith Alone: Issues and Evidence.)
Many excuse the sins and false teachings of say, the Pope, Word Faith teachers, Kansas City Prophets and other groups like them teaching abominable heresy. Even in the case of Anti-Trinitarians like TROTKP author Itzhak Shapira, some have also excused his false christology.
As I have said before, What about their doctrine? Even if the person has a quality life and a supposed repentance, We are not automatically assume they are from the Lord, because repentance is not the only criteria of truth and neither is a holy life the only criteria. Doctrine encompasses what you teach and how you live.
The individuals I have mentioned and other groups I can list, It doesn't matter how many good works they accomplish, If they are not right with God and if they teach falsehood, they are wasting their time.
That's really all I have to day on this matter.
For info, read the following papers:
See the following on some of Rome's atrocities: http://www.reformedapologeticsministries.com/2014/03/some-of-roman-catholicisms-worst.html