Just preach the Word. Don't rely on church growth experts. Thanks, James White, for the insight. Barna may have some great statistics, but don't let them detract you from preaching the word, even the offensive stuff.
"No one is able to come to me unless the Father draws him," says Jesus.
John 6 is full of offensive statements. Just the day before, 10,000 adults (who had just been miraculously fed) wanted to make Jesus king. He was sitting on top of the world. What potential! God could use that. Why did he have to put people off like this: "You are of your father, the Devil." It's almost as though Jesus is sabotaging His own ministry. Many a psychologizer would try to prevent Jesus from pruning like He did.
But Jesus came to do the will of the Father. John 6:37-40 "37. All that the Father gives me will come to me, and whoever comes to me I will never cast out. 38 For I have come down from heaven, not to do my own will but the will of him who sent me. 39. And this is the will of him who sent me, that I should lose nothing of all that he has given me, but raise it up on the last day. 40. For this is the will of my Father, that everyone who looks on the Son and believes in him should have eternal life, and I will raise him up on the last day." John 6:44 "No one can come to me unless the Father who sent me draws him. And I will raise him up on the last day."
John 6:63-65: "63. It is the Spirit who gives life; the flesh is no help at all. The words that I have spoken to you are spirit and life. 64. But there are some of you who do not believe." (For Jesus knew from the beginning who those were who did not believe, and who it was who would betray him.) 65. And he said, "This is why I told you that no one can come to me unless it is granted him by the Father."
Another logic tidbit, v. 37 is the sufficient clause, v. 44 is the necessary clause. In other words, it is necessary and sufficient that the Father draw one, in order for that one to become a faither, i.e., to come to Jesus.