Origin and Application:
Paul was a devoted missionary whose footprints in spreading the gospel could be seen across Asia and Europe. When he preached, he accommodated himself to suit people of different cultures. He would behave differently in front of different audiences in order to gain their friendship and later, the salvation of their souls.
When you become all things to all men, you please everyone – which implies an element of hypocrisy, too. This is hard to achieve in reality. So, this phrase is more often used in negation: you can’t be all things to all men.