My mom talked about this yesterday in Sunday School. She pointed out how we are the salt of the earth, but not everyone is a fan of salt. Have you ever bitten into food that had too much salt on it, and you face kinda wrinkled up in disgust? That is how it is for some nonChristians when they hear the word of God. They can't handle our salt. It is not flavorful, but disgusting to them. Some people can take a little salt, some people can take a medium amount of salt, and some people love salt. As such, you have to treat each nonChristian accordingly. If the nonChristian doesn't want to hear about God, we should not force it on them. They will only be repulsed, and shy from Christianity.
Trying to teach Christian beliefs to nonChristians who do not have the same moral standard as we do is like forcing spoonfuls of salt into their mouths. It will disgust them, and turn them away from ever reaching out to God.