Here’s a post on practical evangelism by Christian scholar Don Johnson.

His list of reasons why people often reject Christianity:

1. Christians behaving badly
2. Disappointment with God
3. Weak or absent father
4. Social pressure
5. Cost of discipleship
6. Immorality (especially sexual immorality)

And here’s the detail on #6:

Of all the motivations and reasons for skepticism that I encounter, immorality is easily the most common. In particular, sexual sin seems to be the largest single factor driving disbelief in our culture. Brant Hanson calls sex “The Big But” because he so often hears this from unbelievers: “’I like Jesus, BUT…’ and the ‘but’ is usually followed, one way or the other, with an objection about the Bible and… sex. People think something’s deeply messed-up with a belief system that says two consenting, unmarried adults should refrain from sex.” In other words, people simply do not want to follow the Christian teaching that sexual intercourse should take place only between and man and woman who are married, so they throw the whole religion out.

The easiest way to justify sin is to deny that there is a creator to provide reality with a nature, thereby denying that there is any inherent order and purpose in the universe.

Aldous Huxley admitted that this is a common reason for skepticism:

I had motives for not wanting the world to have a meaning; consequently I assumed that it had none and was able without any difficulty to find satisfying reasons for this assumption…. Those who detect no meaning in the world generally do so because, for one reason or another, it suits their books that the world should be meaningless. …

For myself as, no doubt, for most of my contemporaries, the philosophy of meaninglessness was essentially an instrument of liberation. The liberation we desired was …liberation from … a certain system of morality.  We objected to the morality because it interfered with our sexual freedom…. There was one admirably simple method in our political and erotic revolt: We could deny that the world had any meaning whatsoever. Similar tactics had been adopted during the eighteenth century and for the same reasons. (Ends and Means, 270-273)

Indeed, similar tactics have been used extensively up to the present day. If you are looking for two great resources that document the extent to which the work of the world’s “great” atheistic thinkers has been “calculated to justify or minimize the shame of their own debauchery,” (Spiegel, 72) I recommend Intellectuals by Paul Johnson and Degenerate Moderns: Modernity as Rationalized Sexual Misbehavior by E. Michael Jones. The bottom line is that these skeptical scholars didn’t reach their conclusions by following the evidence where it led. They didn’t “discover” that the world was meaningless and then proceed to live accordingly. They lived sinful lives (usually involving some type of sexual deviancy) and then produced theories that justified their actions.

This connection between immorality and unsound thought is clearly scriptural. Paul tells the Ephesians that they “must no longer live as the Gentiles do, in the futility of their thinking. They are darkened in their understanding and separated from the life of God because of the ignorance that is in them due to the hardening of their hearts.  Having lost all sensitivity, they have given themselves over to sensuality so as to indulge in every kind of impurity, with a continual lust for more” (Eph. 4:17-19) Paul blames futile thinking and a lack of understanding on hard hearts. When we compare this passage with Romans 1, it seems that immorality and bad ideas work together in a vicious cycle that spirals downward. Sin leads to false philosophies which then lead to more sin.

The wrath of God is being revealed from heaven against all the godlessness and wickedness of men who suppress the truth by their wickedness, since what may be known about God is plain to them, because God has made it plain to them. For since the creation of the world God’s invisible qualities—his eternal power and divine nature—have been clearly seen, being understood from what has been made, so that men are without excuse.

For although they knew God, they neither glorified him as God nor gave thanks to him, but their thinking became futile and their foolish hearts were darkened. Although they claimed to be wise, they became fools and exchanged the glory of the immortal God for images made to look like mortal man and birds and animals and reptiles.

Therefore God gave them over in the sinful desires of their hearts to sexual impurity for the degrading of their bodies with one another. They exchanged the truth of God for a lie, and worshiped and served created things rather than the Creator—who is forever praised (Rom. 1:18-25)

So Paul argues that the nature of reality is clear to everyone but people suppress the truth by their wickedness. Rebellious people become fools as they deny the obvious meaning of creation because of their sin. Their foolishness leads them to indulge in more immorality. Thus immorality is very closely linked to skepticism and we need to be aware that sin will almost always be at least an underlying issue in our conversations.

This post is of such high quality and has such practical wisdom in it that I really want everyone reading to click through and read it. I’m sure you’ll really like it. I recognize every one of these types of people in non-Christians that I have known.

Mr. Johnson’s bio seems to suggest that he has a lot of experience as a pastor, but he’s not like many pastors that I’ve known. If all pastors could interact with so many different sources like and weave together an argument like this, we wouldn’t be in the mess we’re in.