There are a lot of different views regarding how we should preach Christianity. On the one hand, there are those who think we should do everything we can to avoid offending people, even if that means altering our theology in order to make the faith more palatable to some unbelievers. On the other hand, there are those who are so zealous that they just don't care who is offended. Preach the truth in any way necessary, even if it means being a jerk. If you're offending people, you're doing it right. If you're not offending people, you're probably some crybaby Liberal.
Biblically speaking, as usual, the middle ground is the best option. On the one hand, truth will sound like hate to those who hate the truth. Sometimes, you will offend people just by preaching the truth. But are they right to be offended? In truth, it depends. Spot the difference between these two statements:
"All have sinned and fallen short of the glory of God, and the wages of sin is death."
"You're heading to Hell because you're a complete #@$!"
The answer should be obvious. The first is a Biblical truth stated almost exactly as the Bible says it. The other, while the first half is true, shows a lack of respect for the person. The bad news can be stated without insults or hatred. If it offends people to hear the truth, that's one thing, but if they're offended because you're being a jerk, it doesn't matter that you're right, you're still in the wrong.
That's the bad news, but what about the good news? It's possible to deliver that wrong, too. Once again, spot the difference between these two statements:
"In spite of your sin, God loves you, and so He poured out His wrath upon Jesus on the cross. If you repent and trust Him, you will be saved."
"It takes a special kind of moron to see the evidence for the resurrection and still not become a Christian."
Once again we have the same truth stated in a different way. The former states a Biblical truth in the hope the recipient will accept it. The latter is a personal attack on those who don't.
It is an unfortunate fact of human nature that we disrespect each other in some of the most vicious and unacceptable ways. But this is something we are called to repent of. Even if you are talking to a legitimate enemy, a gentle response turns away anger, yet a harsh word generates strife. Therefore, it is both more productive, and more importantly it is more honouring to God, when we gently and respectfully share the Gospel with the lost. People's sin is not an excuse to join in. If you must offend people, it is essential that you make sure they are wrong to be offended. If they're right to be offended, you messed up, and need to repent.