"Yet they are not all alike. - Some of the People of the Book are an upright people." (Al-Imran 3:113)

Using this Qur'ānic framework, we can differentiate the characteristics of these two groups:

Pious, Good Christian
Heretical Bad Christian

MORALITY:

-Free from pride (5:83)

-Trustworthy with lent gold (3:74)

-Enjoin justice, forbid evil (3:113)

-Vie with each other in piety (3:113)

-Righteous (3:113)

-Compassionate and merciful (57:27)

MORALITY:

-Untrustworthy, tight-fisted (3:74)

-Shamelessly break faith (3:75)

-Evil-doers (3:111)

-Rebels and transgressors (3:112)

-Consumed with rage (3:120)
THEOLOGY & DOCTRINE:

-Believe in God and the Last Day (3:113)

-They worship God and worship sometimes all night (3:113)

-They instituted monasticism with good intent, but they did not observe it faithfully (57:27)

-They have nothing to fear (5:69)

-They will be rewarded at judgment (3:113)
THEOLOGY & DOCTRINE:

-Believed God had a wife and thereby a carnal God-son (Surah 6:101, 72:3); they say "God has taken (borne) a son" (10:68)

-They believed in three separate gods: Jesus, Mary and Allah (5:116). They say God is one of three (5:73)

-They think they can control God's grace (57:29)

-They discriminate against Abraham, Ishmael, `Īsāac, Jacob, Moses and the Jews.
ATTITUDE TO SCRIPTURE:

-Recite their scriptures (3:113)

-Read it with the right reading (2:121)

-Believe in them (2:121)

-Judge by their scriptures (5:47)
ATTITUDE TO SCRIPTURE:

-Throw away the Book of God behind their back as though they didn't know it (2:101)

-Knowingly say untruths of God (3:76)

-Knowingly conceal the truth (2:146)

-Ignorant of scriptures, they know nothing but wishful fancies and vague conjecture (2:79)
VIEW OF JESUS:

-Say Masih was God's servant (4:172)

-Say Messiah was God's Word
 

VIEW OF JESUS:

-They deny Jesus' humanity (5:75) and claim that Jesus said, "Worship me instead of God" (3:79) and "Serve the angels and the prophets as your Gods"
ATTITUDE TO MUSLIMS:
-"You will find ... that the nearest in affection to them [Muslims] are those who say: ‘We are Christians.'
ATTITUDE TO MUSLIMS:

-They do not love Muslims (3:119)

-Rejoice at Muslims' harm (3:121)

-Enemies of Muslims (5:82)

It is clear from the above list that the "pious" Christian lines up with the teaching found in the Injiil, while the "evil" described above represents a small heretical group with a non-scriptural viewpoint. The Qur'an must be describing a Christian heresy which taught that God had sexual relations with Mary (God forbid!) and Jesus was the semi-God result.

Historical records show that the "bad faction" described in the Qur'an represents a very small faction of Christianity which would have been rejected by the majority of Christians at that time as well.


From this table, we see that while the Qur'an condemns a heretical faction of false Christians who taught three Gods and twisted the meaning of the Gospel, the Qur'an also speaks positively about the true Christians who follow the Gospel, recite it correctly, and believe in God and the Last Day, telling them they would be judged by their own scriptures.  link; Qur'an