The question may be phrased in many different ways:

There is no easy answer for this question either.

I believe that the explanation may be found in the nature of love. More than anything, God wants us to love him (and thus, of course, also love all our fellow human beings).

But love must be voluntary. You can't force another person to love you. If you are sufficiently powerful, you may force other people to behave as if they love you, but it wouldn't be love, for love must spring from a free choice.

Of course, God could have created us so that we blindly obeyed him. But that would have made us into mindless robots. Instead he decided to give us the possibility of a choice. Our love for him (and thus our faith in him) thereby became a voluntary thing – he doesn't force us.