Most people try to pass along their beliefs to their children. Even the atheists that claim that all religious education is child abuse are, by virtue of making such a claim, demonstrating a dominant worldview claim that they hope their children will latch onto.
The rationale for this is simple. If someone actually believes his religion is true in an objective way, then it follows that he will hope his child will also believe that the same religion is true. This is because truth about the world tends to make the world easier to live in.
For the sincere Christian believers, the content of their belief may be passed to their children either as thick belief or as thin belief. Surely there is room on the spectrum between these points for degrees of each, but the ends of the scale are useful to illustrate my point.
What is Thick Christianity?
Thick Christianity is a doctrinally sound, ethically rich, gospel saturated faith. This is not to say that it is overflowing with systematic theology (though it may be), or that every choice made is moral (which it certainly won’t be), or even that conversion will occur in the children. Conversion is the work of the Holy Spirit, thus even when thick Christianity is communicated some children may never be born again. However, children who have been exposed to thick Christianity will be able to explain the content of and rationale for the Christian faith whether they have personally accepted it or not.
I have heard it said, though I no longer remember by whom, that in one generation the gospel is loved and known. In the second it is assumed. In the third it is forgotten and abandoned.
This pattern can be witnessed in the fall of once boldly Christian institutions into a malaise of unbelief within a few short generations. A prime example of this is Oberlin University in Ohio. Once it was a robustly Christian institution, but a search of the website now reveals that the gospel is no longer central to their mission. The same phenomenon can occur in churches and denominations. A congregation that was once vibrantly faithful can so easily fall into cultural Christianity in a few years if the central message of the gospel is assumed for a while. Later it will likely be neglected and changed or forgotten. At that point a church becomes a social club and a university becomes just another non-profit educational establishment. There is still some value for society in these mediating institutions, but the transformational power of the gospel is lost.
Thin Christianity is more subject to this sort of generational attenuation than is thick Christianity because thin Christianity lacks the substance that would sustain it. We should expect this, because early in Scripture we get evidence of the importance of living thickly for the propagation of faithfulness between generations.
In Deuteronomy 6, which is part of Moses’ farewell to the Israelites, he affirms the important theological truth of the oneness of God. (v. 4) Then he commands them, “You shall love the Lord your God with all your heart and with all your soul and with all your might. And these words that I command you today shall be on your heart.” (vv. 5-6) In other words, theological truth must result in right ethical action for the believer. The oneness of God led to worship both through adoration and through action. This is part of living a thick Christianity and not merely being a hearer of the word. (cf. Jas. 1:22)
But there is more to the story. Immediately after this Moses gives another command to his audience, “You shall teach them diligently to your children, and shall talk of them when you sit in your house, and when you walk by the way, and when you lie down, and when you rise.” (v. 7)
The significance of verse 7 is not that teaching should be done when sitting, walking, lying down, or rising, but rather that all of life is teaching opportunity for communicating a thick Christianity to our children. Teach them not just the “what” of Christianity, but the “why.” This is what makes a Christianity thick. It is a form of Christianity that is lived, authentic, and grounded in substance. This is the sort of Christianity that has a hope of being sustained across generations.
Ultimately, God does the work of salvation in our children. However, if our Christianity is true, it makes sense to live it in such a way that our religion cannot be reduced to a weekly routine or a set of prohibitions.
What is Thin Christianity?
Despite what some might expect, a thin Christianity is not necessarily unorthodox. Someone can be a faithful Fundamentalist with (mostly) biblical doctrine and live a thin Christianity before their family. There are many faithful Christians that have the right doctrine, but they often do not know why. In other cases, they do understand the basis of their doctrine, but fail to communicate it effectively to their children.
The difference is the depth of living in Christ. Our kids are with us all the time and they can tell when we’re going through the motions. Thin Christianity may have all the right motions, but it is often missing the most important emotion: joy.
A Call to Live Christianity Thickly
Thankfully, sometimes God takes thin Christianity and uses it to make Christians that live thickly. Grace is a wonderful thing.
But it is a much better thing to pass on a thick Christianity to our children. That way they get the benefit of doing the right things for the right reasons, of being faithful and experiencing the joy of knowing Christ richly, and of being able to reference a heritage of thick Christianity when they live well before their children. And by living well I don’t mean getting everything right, I mean pursuing the joy of the Lord in all things.
This is, I think, what Paul was getting at when he wrote Colossians 3:12-17:
Put on then, as God's chosen ones, holy and beloved, compassionate hearts, kindness, humility, meekness, and patience, bearing with one another and, if one has a complaint against another, forgiving each other; as the Lord has forgiven you, so you also must forgive. And above all these put on love, which binds everything together in perfect harmony. And let the peace of Christ rule in your hearts, to which indeed you were called in one body. And be thankful. Let the word of Christ dwell in you richly, teaching and admonishing one another in all wisdom, singing psalms and hymns and spiritual songs, with thankfulness in your hearts to God. And whatever you do, in word or deed, do everything in the name of the Lord Jesus, giving thanks to God the Father through him.