Often ‘the church’ can say and do really stupid, even horrible, things in the name of Jesus. Individual Christians do the same. Whether by word or behaviour individuals and churches can put others off Christianity. This is a bad thing.
Yet Jesus himself offended people, he appears to have even done so on purpose:
When many of his disciples heard it, they said, “This is a hard saying; who can listen to it?” But Jesus, knowing in himself that his disciples were grumbling about this, said to them, “Do you take offense at this? Then what if you were to see the Son of Man ascending to where he was before? 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. 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.) And he said, “This is why I told you that no one can come to me unless it is granted him by the Father.”
After this many of his disciples turned back and no longer walked with him. (John 6:60-66 ESV)
In the discourse of John 6:25-58, Jesus had spoken words of truth to a large crowd of people. What he said offended them, not because it was hard to understand but because what they did understand was offensive. Jesus fully knew it would offend them and he would lose followers but spoke the truth to them anyway. He had no problem with a huge crowd turning away from following him, leaving only twelve disciples.
We must always speak the truth in love (Ephesians 4:15), but there will be some occasions when the words of Jesus, in fact Jesus himself, is offensive to people and they will turn away. This is heartbreaking, I don’t care how much of, or what kind of, a sinner anyone is the last thing I want is for them to be eternally excluded from fellowship with God. Yet even comprehending the truth — understanding the meaning of the words — some will refuse to follow Christ.
Theology lets us down on the topic of predestination, but Jesus makes it clear enough that unless God enables it to happen, nobody can come to Jesus. So in those awful times when somebody is offended by Christ and cannot see his beauty the most useful thing I can do is pray. I can pray fervently, desperately, that God will grant for that person to see the glory of God in Christ Jesus.
But thanks be to God, who in Christ always leads us in triumphal procession, and through us spreads the fragrance of the knowledge of him everywhere. For we are the aroma of Christ to God among those who are being saved and among those who are perishing, to one a fragrance from death to death, to the other a fragrance from life to life. Who is sufficient for these things? (2 Corinthians 2:14-16 ESV)