>As Christians should we be spreading the word of god where ever we can, even if it will offend?
Yes, many pagans were often offended by the the teachings of Christ, many people died because of spreading the word of god and still do. Also, Christ died because the pharisees were offended of his teachings.
Mark 16:15
>And he said to them: Go ye into the whole world, and preach the gospel to every creature.
Matthew 28:19
>Going therefore, teach ye all nations; baptizing them in the name of the Father, and of the Son, and of the Holy Ghost.
>When is it not appropriate?
There is a never a time were it's inappropriate