Who are you challenging?!? I don't know of any believer that supports or promotes this, so not sure where you're getting this from?
Sin is sin, but there is a difference between a sinful lifestyle and a sinful temptation, and I think this is where the confusion is.
The scripture that comes to mind...
1 Cor 6:9-11: Do you not know that the unrighteous (non believers) will not inherit the kingdom of God? Do not be deceived. Neither fornicators, nor idolaters, nor adulterers, nor homosexuals, nor sodomites, nor thieves, nor covetous, nor drunkards, nor revilers, nor extortioners will inherit the kingdom of God. And such were some of you (believers). But you were washed, but you were sanctified, but you were justified in the name of the Lord Jesus and by the Spirit of our God"
The ones involved in/"living in" such sinful lifestyles are non believers, lost in the world, who have not been convicted of their sins yet. It says "And such were some of you" as in some believers used to be involved in those lifestyles before they became new creatures in Christ. They don't go back to that life.
As for believers, we are not sinless, because while we have these bodies we will always struggle with the sin nature. So believers will occasionally fail, whether they have a wrongful thought or get angry. Still wrong, but this is not the same as living in a sinful lifestyle. A believer does not go back to life as a thief, or back to a homosexual lifestyle, for example.
Romans 7:14-25:
"For we know that the law is spiritual, but I am carnal, sold under sin. For what I am doing, I do not understand. For what I will to do, that I do not practice; but what I hate, that I do. If, then, I do what I will not to do, I agree with the law that it is good. But now, it is no longer I who do it, but sin that dwells in me. For I know that in me (that is, in my flesh) nothing good dwells; for to will is present with me, but how to perform what is good I do not find. For the good that I will to do, I do not do; but the evil I will not to do, that I practice. Now if I do what I will not to do, it is no longer I who do it, but sin that dwells in me.
I find then a law, that evil is present with me, the one who wills to do good. For I delight in the law of God according to the inward man. But I see another law in my members, warring against the law of my mind, and bringing me into captivity to the law of sin which is in my members. O wretched man that I am! Who will deliver me from this body of death? I thank God—through Jesus Christ our Lord! So then, with the mind I myself serve the law of God, but with the flesh the law of sin"