In this age of tolerance, what is the most effective way to communicate an intolerant gospel?

Great question.  The Gospel message is of course the same no matter what age you are proclaiming it in, but in each unique context people will have different objections to it.  For example, the truth that there is only one way to God is offensive to people in our culture, but assumed by most people in the Middle East (as it was in the West before the Enlightenment).  Each time and context has it’s own set of objections to the Gospel.  By your question I assume that you are aware of this and you want to understand how to communicate the unchanging Gospel to the place God has called you.  These have been very helpful to me:

The Heart of Evangelism (book), Jerram Barrs (his free podcast with the same content)

The Reason for God (book), Tim Keller (audio book) – Great book directed to unbelievers where he explains the Gospel and answers objections

Who is This Jesus? (free audio) and Prodigal Sons (free audio), Tim Keller

The Prodigal God series (free audio), Tim Keller

Objections to Christianity series (free audio), Tim Keller