Since I have explained my stance in very detailed manner so i would not like to bore people with repeating same stuff again and again like some people do here 
rather i try explian you by giving an easy to absorb real world example – ( now dont think too much into it ; its just analogy )
In near future, NASA is planning to send a man on mars. They are looking for a suitable person for this manned missoin. After riggorous search they reach to the conclussion that only one person fulfills their criteria. That is a young , smart , handsome and energetic pakistani expatriate named ‘AQ’. He is truly a gem. NASA send team and call him at their headquaters
NASA people tell him that they are going to make him an offer, he cant refuse.
Now this is what they tell him :
**1. NASA is going to train you , and send you to planet MARS on a return trip. **
2. You will be our deputy on that planet and you will have to follow the commands of NASA in letter and spirit
3. This will be a short trip. You will return back to earth (your native planet)
4. Remember this is a returm trip. You will eventually come back to planet earth after the completion of mission. You will stay at MARS for a very short period of time and during that time we will monitor you activities.
5. If you obeyed our orders, then after your return you will be granted permanet citizenship of heav… err United States of America. But if you failed then we well extradite you back to Pakistan and you will live rest of your life there
^ I hope now this is very easy to grasp example, even a layman can understand the concept. I hope you know that deputy means *Khalifa *in Arabic
At any stage of debate running out of arguments is natural for anyone but please dont confuse the readers 
We are discussing concept of Rasool w.r.t the story of people who came to prophet Ibrahim and Lut (pbut) not regarding Prophet suleman (pbuh)