Greg Koukl, in his October mentoring letter:2014-10-13 11.55.02

Some pastors think apologetics is window dressing, fine for those who like that sort of thing, but an extravagance, a non-essential. Agreed, not everyone will make a vocation of defending the faith. But sooner or later each Christian will be forced to face the harshest critic of all: his or her own inner doubts.

That’s right, the toughest opponent you’ll ever have to confront is you. Someone once said, “The heart cannot believe what the mind rejects.” This is also obvious. If you’re not confident the message of Scripture is true, you can’t put your trust in it even if you tried. Trust cannot be manufactured. Faith cannot be squeezed out by acts of sheer will.

However, if you get your hands on substantiating evidence—if you find out the facts and are equipped with compelling reasons—your confidence grows automatically, deepening and invigorating your faith.