"It seemed good to the Holy Spirit and to us not to burden you [Gentile Christians] with anything beyond the following requirements: You are to abstain from food sacrificed to idols, from blood, from the meat of strangled animals and from sexual immorality." - Acts 15:28-29
Ah, now to define immorality...
Immoral: Not conforming to accepted standards of morality.
Oh, Sweet.
That Cleared Up So Many Things.
Fortunately in this instance we have a fairly clearly-defined guide to what is and is not sexually immoral. Not all of it is relevant, but it goes by the names of the Mosaic Law, the Pentateuch, or Exodus, Leviticus and Deuteronomy depending on who you ask.
Another thing Jesus taught that a lot of Christians seem to forget, is that it's OK if people don't believe in God or Christianity. You can preach all you want, but you can't force people to change their minds. I specifically remember something about seeds in a field falling on paths and rocks? Arx, you're sharing Bible quotes, help me out here.
You're thinking of the
Parable of the Sower, in which Jesus describes how people
a) hear the Word but don't understand it
b) understand it but give up easily
c) hear it but don't want to follow it and
d) sometimes actually follow it.
And I'm in complete agreement with you. Trying to force people to believe is counterproductive.