The people of Colossae were on board with the Gospel because they had heard it, and understood it.
…the gospel, which has come to you, as indeed in the whole world it is bearing fruit and increasing—as it also does among you, since the day you heard it and understood the grace of God in truth.
Col 1:5c-6
We have been entrusted with speaking the Gospel, and speaking it in such a way that the hearer can hear and understand.
Jesus snuck that same truth in the climax of the parable of the four soils:
As for what was sown on good soil, this is the one who hears the word and understands it.
Mt 13.23
For the missionary this, most likely, means learning a language.
For the person speaking to kids, it means keeping it simple and interesting.
A person sharing with teens has the challenge of matching their vibe.
For all of us, it means not using our coded Christian diction:
“...the eternal ramification of sin is unquenchable fire.”