The fact that there’s always a residue of people in each dispensation that holds firmly to the truth applicable to the dispensation they live in, doesn’t mean that we aren’t supposed to preach the gospel in order to get people saved. We need to preach it because we do not know who is going to believe it.
Preaching the gospel should always be our top priority. We cannot force people to believe though. Our work is to give them the gospel and once that is done, our mission is accomplished.
One has to take into consideration that some people will not see the truth immediately. It took me a good few years to believe that my good works will never get me into heaven. I was oblivious to the fact that there was more than one gospel in the Bible, nor did I see the exclusivity of the Apostle Paul’s ministry as it applies to everyone today. I wasn’t even aware of what the gospel was that saved my soul.
I’m of the opinion that the longer and harder it takes for one to see the truth, the more one appreciates it and one doesn’t want to see it corrupted, as opposed to someone who was born into a family who knew the truth and it gets handed to you on a silver platter.
Once you’ve been deceived countless times – you are more prone to ensure you never end up there again.