The key principle in any truly effective communication is: Know Your Audience! - who are you speaking to? I think Jesus, John the Baptist and the Apostles were masters of this as they ministered.
When John spoke to the crowds who came to him for baptism, he spoke in such a way that the common people were touched to the point that they confessed their sins and were baptised.
Interestingly, several years ago, I had an opportunity to speak with a Hasidic Jew about his faith. I asked him to tell me what I would need to do in order to become a Hasidic Jew if that were something I wanted to pursue. He explained that I would need to live with a Hasidic family for some time so they could observe my life to make sure I was sincere and serious. Then, if they concluded that I was a worthy candidate, I would need to be baptised. I was shocked to hear that. In order for a "pagan" to become a Jew, he would have to be baptised! And, then, I began to realize the significance of John's baptism. He was basically saying to the people, "You have been living your lives in such an ungodly way that you need to be treated like pagans! Therefore, turn from your sins, and be baptised just like the pagans need to do to become Jews!"
When John saw the Pharisees and Sadducees coming to where he was baptising, he spoke to them very straightforwardly, calling them a brood of vipers, and telling them to produce fruit in keeping with repentance - ie. don't just say you repent and be baptised, make sure you really do change your hypocritical lives!
Jesus, too, understood his audience. When speaking to the woman at the well, He is pointed, but very compassionate. When speaking to the Pharisees, He is pointed and almost harsh - "Woe to you, hypocrites . . . blind guides, etc."
When Jesus or the Apostles spoke to Jews, they knew that their audience had been prepared to understand the message. They knew the Scriptural teaching about the nature of sin, the nature of God and the nature of salvation. They understood the need for an innocent life to be given in order for the sins of a guilty life to be covered over. Thus, when John says, "Behold, the Lamb of God," his audience understood that he was not saying, "Hey, here comes a fuzzy, dumb, fearful wimp!" Rather, they understood that Jesus was the innocent One who had come to be the substitute offering for their sins. As the Apostles spread their message to Jews, they were building on the knowledge that they already had from being part of the Jewish culture.
When Paul speaks to the Gentile philosophers on Mars Hill, he takes a totally different approach. He doesn't quote Scripture, because they didn't see Scripture as authoritative for them. He actually quotes from their writers and culture as he addresses them, and relates his message to his audience.
The US was in a place similar to the Jews of Jesus' and the Apostles' time in the 1950's - people had an understanding of the terms of Christianity, and simply needed the dots to be put together. Today, we are more like the Gentiles that Paul spoke to on Mars Hill. In order for us to be effective in our witness, we need to understand what our audience knows and doesn't know, and tailor our messages to them.
I'm always amazed when I hear preachers giving salvation messages week after week to their congregations when 99% of their audiences are Christians or have heard the same basic message many, many times. Then, they go out into the marketplace for an outreach to non-believers and, basically, hold a church service with hymns and preaching, and communicate in such a way that often is totally unaware of who they are really speaking to.
If we are to be effective communicators, we need to know our audience, and adapt our messages accordingly.