Well, the catching up has not happened yet, so this would make Paul a liar by how you understand what he said, or that you might not understand the full context of 1 Thessalonians 4:13-18 as "we" means those who are still alive at His coming.Paul is speaking of himself being eligible to be caught up with all others on the day he said this .
He does not say " Then those which will be alive and remain.." speaking of the future.
Paul instead speaks in present tense when he says , WE WHICH ARE ALIVE. leaving no doubt he believed that the catching up could happen the day he talked about it .
In Matthew 24 the disciples asked Jesus three questions, Tell us, when shall these things be? and what shall be the sign of thy coming, and of the end of the world? Jesus told them of all things which must come first before His return as we read from vs 4-28. The greatest sign of His one and only return is found in Matthew 24:29-31, but yet no man will know the day or the hour as even Christ does not know, but the Father only, but gave us a clue that that day will be like the days of Noah for when the flood came those without faith in God were swept away in the flood only saving Noah and his family, Matthew 24:36-39.