That always confounded me - why on earth would an earnest religious person turn away someone from their church, just because they were a sinner? Aren't non-christians the people you -want- to come to church? Afterall, Christ did lunch with sinners, and preached love and compassion. It's become clear to me that many christians (but not all) are not interested in saving souls, but only about their social club that lets them feel superior to people who are not Them - the other, the different, the outsider. It used to be the jews and gypsies until it became unpopular to ostracise them - now it's the gays and muslims.
The key phrase there being "earnest religious person". This does not automatically infer someone is a christian. Applying that same phrase to a muslim, would you assume an "earnest religious person" is a muslim because they blow themselves up? Of course not.
1 Corintians 5:
9 I wrote to you in my letter not to associate with sexually immoral people— 10 not at all meaning the people of this world who are immoral, or the greedy and swindlers, or idolaters. In that case you would have to leave this world. 11 But now I am writing to you that you must not associate with anyone who claims to be a brother or sister[c] but is sexually immoral or greedy, an idolater or slanderer, a drunkard or swindler. Do not even eat with such people.
12 What business is it of mine to judge those outside the church? Are you not to judge those inside? 13 God will judge those outside. “Expel the wicked person from among you.”
Referring specifically to the "wolf in sheep's clothing", someone who claims to be a "brother or sister" (ie christian) but acts in the complete opposite of the Word's commandments and bearing no fruit as a follower of Christ. As stated in reference to those who make no claims of being part of the body " What business is it of mine to judge those outside the church."
Long story even longer, while as a christian I will not make excuses for the sins people commit (including mine), I am tasked by my lord to inform them that there is a better way. This way allows us all to be forgiven and therefore conquer sin and death resulting in everlasting life with God. The word teaches performing homosexual acts is rebellion against God and the way he made us. I am to denounce the sin, but love the sinner as Jesus teaches:
27 “But to you who are listening I say: Love your enemies, do good to those who hate you, 28 bless those who curse you, pray for those who mistreat you. 29 If someone slaps you on one cheek, turn to them the other also. If someone takes your coat, do not withhold your shirt from them. 30 Give to everyone who asks you, and if anyone takes what belongs to you, do not demand it back. 31 Do to others as you would have them do to you.
32 “If you love those who love you, what credit is that to you? Even sinners love those who love them. 33 And if you do good to those who are good to you, what credit is that to you? Even sinners do that. 34 And if you lend to those from whom you expect repayment, what credit is that to you? Even sinners lend to sinners, expecting to be repaid in full. 35 But love your enemies, do good to them, and lend to them without expecting to get anything back. Then your reward will be great, and you will be children of the Most High, because he is kind to the ungrateful and wicked. 36 Be merciful, just as your Father is merciful.