Matthew 7:7-8, "7 “Ask and it will be given to you, seek and you will find; knock and the door will be opened to you. For everyone who asks receives; the one who seeks finds and to the one who knocks, the door will be opened."
If they came to Christ, Christ doesn't turn anyone away. Maybe they felt pressure to do so and was being nice or whatever happened. Maybe they came, but discovered they had to change too much of themselves or they'd rather keep living life as they are...whatever the reason. Christianity isn't a feeling. It's not about warm fuzzies. It's not about living a comfortable life. We must die to self, take up the cross, and follow Him. The world hates Christ and they hate Christians. You can see that in the world.
If people walk away, it's because they wanted to, not that they didn't find. He's right there, waiting to be accepted. And when He is, He will fill your heart and you become sealed with the Holy Spirit until the day of redemption.
Jesus also said that not everyone who says "Lord, Lord" shall enter the kingdom of Heaven and that's because they never really sought out a relationship with Him. It was all about vanity, a status thing to look good, or a popularity contest. But if Christ says that if you seek you will find, then I believe every single person who turns away from Christ did so out of personal choice and not because they didn't find Him.