Recently I heard, second hand, that a famous preacher had said that our Gospel message is attractive and that people reject it because Christians are not nice people. Not sure where he got that, certainly not from the Bible.
"For we are a sweet aroma of Christ to God among those who are being saved and among those who are perishing—2:16 to the latter an odor from death to death, but to the former a fragrance from life to life." 2 Corinthians 2:15,16
"Remember what I told you, ‘A slave is not greater than his master.’ If they persecuted me, they will also persecute you. If they obeyed my word, they will obey yours too. But they will do all these things to you on account of my name, because they do not know the one who sent me." John 15:20,21
"Blessed are you when people insult you and persecute you and say all kinds of evil things about you falsely on account of me. Rejoice and be glad because your reward is great in heaven, for they persecuted the prophets before you in the same way." Matthew 5:11,12
Now, this is not a warrant to be a jerk. There are negative consequences for the propagation of the Gospel for our misbehavior and positive consequences for our good works.
"Maintain good conduct among the non-Christians, so that though they now malign you as wrongdoers, they may see your good deeds and glorify God when he appears." 1 Peter 2:12
"But set Christ apart as Lord in your hearts and always be ready to give an answer to anyone who asks about the hope you possess. Yet do it with courtesy and respect, keeping a good conscience, so that those who slander your good conduct in Christ may be put to shame when they accuse you." 1 Peter 3:15,16
How should we respond to abuse?
"When we are verbally abused, we respond with a blessing, when persecuted, we endure, when people lie about us, we answer in a friendly manner." 1 Corinthians 4:12,13
Don't be a jerk Christian but don't expect everyone you talk to fall at the foot of the cross and shower you with gratitude. If they do, you aren't preaching the Gospel.
"True evangelism is more like a warrant for arrest on a death penalty offense, with the possibility of pardon for the guilty. True evangelism does not sell: it indicts, and those who submit to the indictment also submit to the saving grace of God." RJ Rushdoony
We don't come preaching with side arms and handcuffs but we do come with a message that indicts. Who likes to be indicted? Don't expect a friendly response. If you get a positive response it will be because the Holy Spirit is calling and convincing them, because He is adding them to the ranks of the saved, because they are elect and predestined.
A hostile response does not mean you were not nice enough. We are commanded to be obedient, which includes being kind to those who persecute us. We are not commanded to make them judge us as "nice" according to their pagan standards. Your very obedience, even treating them kindly according to God's standards, is an indictment. They will likely hate you for it.
“Men question the truth of Christianity because they hate the practice of it.”
 Rushdoony, Rousas John. Salvation & Godly Rule. Vallecito, CA: Ross House Books, 2004, pp. 568-569
 JC Ryle, Thoughts for Young Men, p. 5