Many evangelistic endeavors seek to bring people out of false religions and cults. Those are very important and have accomplished great things.
But their value isn’t just in getting people out of bad things, it is in keeping people from entering them to begin with.
You may be able to count how many people a group converted from Mormonism, for example, and it may seem like a small number. But keep in mind that good teaching may have prevented many more people from entering Mormonism to begin with. It is just that the defensive numbers don’t lend themselves to tracking as well as the offensive ones do. But both are important.
In the same way, apologetics may seem focused on getting people out of cults and other religions and converting them from atheism. But it can help keep people from leaving the church (many of whom are unsaved). I’m not disputing the “once saved, always saved” teaching that I hold to. I’m just saying that you can’t just assume people are saved because they show up at church wearing nice clothes (I know that of which I speak, as I used to be one of those nicely dressed pagans sitting in the pew).
So my strategy is to spread sound teachings far and wide and play both offense and defense.