The answer to this question will surprise many, but  yes, all Christians are called to ministry.  Most Christians view "witnessing" as if it meant "witness protection program" and are running from lost souls as if they were the new H1N1 virus.  It's something to think about; if you were arrested for being a Christian, would there be enough evidence to convict you? or would you be exonerated for being an imposter.  But I digress, in Matthew 28:18-20  "Then Jesus came to them and said, "All authority in heaven and on earth has been given to me.  Therefore go and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, and teaching them to obey everything I have commanded you.   God is telling not only the disciples in this passage, but to everyone who hears the gospel and believes to obey the great commission.  This is in affect your ministry, an opportunity to reach out and witness the good news–It's a good thing to save souls for Christ Proverbs 11:30.  Jesus spoke to Peter and said that he would be a fisher of men, also referring to his body of followers.  When we sit around and say, "I'm not in the ministry," or "I don't want to be a preacher," we thwart the very plans of the Almighty  When we got "saved", we were saved unto good works, which therein lays our "ministry" and also known as "our calling".  So the next time you hear the phrase, "called to the ministry", that doesn't mean that you will be up-behind the pulpit spewing fire and brimstone from the heavens, it just may mean you've been called to go help that old lady across the street and then give a reason for the love that has been bestowed deep down in your heart that God has been trying to reach for the last 90 years.  Our  ultimate goal is to wins souls for the King so that they may have the same eternal life that we do.