Was Paul speaking to lost people?

Lutero said:

Was Paul telling lost people or saved people in verse 13 - for it is God who works in you both to will and to do for His good pleasure? As far as running or laboring in vain. What about those works that are burned up at the Judgment (1 Corinthians 3:13-15) but the believer is STILL SAVED? Was that running and labor in vain in regards to those works?

Whether they were lost or saved, God knows. I don't know those people from Adam. All I know is that St. Paul was addressing them and giving them guidance unto salvation. Which, if they listened and obeyed, God would save them on the last day. 

Sincerely,

De Maria