For the "Christian" celebrities in particular, some of them are only externally-culturally Christians. For example, Carrie Prejean, Carrie Underwood, Toby Keith's family, Blake Shelton and Miranda Lambert-- they all claim Jesus; but:
15 “Beware of false prophets, who come to you in sheep’s clothing, but inwardly they are ravenous wolves. 16 You will know them by their fruits. Do men gather grapes from thornbushes or figs from thistles? 17 Even so, every good tree bears good fruit, but a bad tree bears bad fruit. 18 A good tree cannot bear bad fruit, nor can a bad tree bear good fruit. 19 Every tree that does not bear good fruit is cut down and thrown into the fire. 20 Therefore by their fruits you will know them.
21 “Not everyone who says to Me, ‘Lord, Lord,’ shall enter the kingdom of heaven, but he who does the will of My Father in heaven. 22 Many will say to Me in that day, ‘Lord, Lord, have we not prophesied in Your name, cast out demons in Your name, and done many wonders in Your name?’ 23 And then I will declare to them, ‘I never knew you; depart from Me, you who practice lawlessness!’
I already covered Toby Keith and his family. As for Carrie Prejean (and I thought, though I could be wrong about, that NotYourTypicalNegro on YouTube was the one who made this point about her), she stated that she believed that homosexuality is wrong only because of her upbringing and not because she really believes that "[n]either 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." For Carrie Prejean ("No offense; that's just how I was raised."), the message of the Cross is offensive:
Therefore, to you who believe, He is precious; but to those who are disobedient,
“The stone which the builders rejected
Has become the chief cornerstone,”
And a rock of offense.”
8 and
They stumble, being disobedient to the word, to which they also were appointed.
And of course the message of the Cross will be offensive; "[f]or the message of the cross is foolishness to those who are perishing, but to us who are being saved it is the power of God." By the way, homosexuality as a thorn in the flesh is (as a like to say) a-whole-nother discussion; but you can't get away with being a Christian and not expect to cause offense-- which I myself have to relearn daily.
As for Carrie Underwood, I don't see a woman who is serious about "Jesus, Take the Wheel"-- especially when she sings songs such as "Before He Cheats". The same goes for Miranda Lambert (e.g., "Kerosene), Blake Shelton's mistress and now wife.
In conclusion, these celebrities tend to have their religion as only their external, not their internal, culture because "that's just how [they] were raised", not how they ever really believed for themselves. The same may go for the parents who raised them (For more on this, ask me about it in the comments section.).