“Each of you should go on living according to the Lord’s gift to you, and as you were when God called you”. 

1 Cor 7:17 GNB 

When a person comes to believe in Christ should he or she look for an occupation where discipleship will be easier and the environment more congenial? The gist of Paul’s advice to the new converts in Corinth was: “No. Stay where you are and live up to your Christian principles there”. “That means a heart-commitment to stay firmly where they were when God first called them into fellowship with his Son, Jesus Christ. This was the wise advice given by a few close friends to the singer Cliff Richard, when many other unwise advisers were urging him to move out of the entertainment business” (D. Prior, The Message of 1 Corinthians, p130). 
The big thing for those early Christians was to see in their new-found fellowship with God an opportunity to make a witness to their neighbours, friends and colleagues. Paul knew that if they exhibited changes in attitudes, life styles, and character it would underline the truth of the message of the gospel of Jesus Christ that he and other apostles were preaching. Notice that he says, “This is God’s gift to you”. He was not so much urging them to be good, but reminding them that the salvation they now knew was God’s gift to them. It would be an even greater gift if they worked it out in the teeth of opposition, ridicule, and doubt. 
A Christian would certainly question some occupations – (e.g. gambling, organized crime and prostitution), but in general the principle Paul lays down there applies to us today in our modern world and equally difficult situations. 

Lord, help believers everywhere to live out their faith daily.