Scripture places the mind under the governance of God for his direction and assistance, and places the passions under the governance of the mind for their restraint and control so that they may be turned into the instruments of justice. In fact, in our discipline, the question is not whether the devout soul is angry, but why; not whethuer it is sad, but what causes its sadness; not whether it is afraid, but what is the object of its fear. To be indignant with the sinner with a view to his correction, to feel sorrow for the afflicted with a view to his release from suffering, to be afraid for one in danger so as to prevent his death - those are emotions which, as far as I can see, no sane judgement could reprove.
Augustine of Hippo, City of God, IX.5.Augustine is sometimes criticised for being too Platonic, too quick to dismiss the emotions and the bodily in favour of the rational soul. But here, he shows quite a dramatic break with the classical tradition regarding the emotions.
Augustine claims that despite their differences, the various ancient schools of thought all basically agree that the wise man will suppress his emotions as much as possible, that the affective life is sub-human and to be transcended through reason. Earlier, he lampoons an example in Stoic teaching of a philosopher who is embarrassed that his face turns pale and his knees shake when he is on a boat threatened with shipwreck. For the Stoic, these unwanted expressions of fear don't belong in a life ruled by reason. The philosopher is to tell himself that the shipwreck can do no harm to his virtue, which is all that really matters and so is to be calm and composed.
Augustine contrasts this with the Christian view, in which the emotions not only have their proper place, but their own rationality. They can be investigated and understood, appreciated and even turned into "the instruments of justice". That is, he thinks that a healthy emotional life is possible in which my feelings are neither forcefully suppressed as irrational manifestations of my bodily nature, nor allowed to rule and make me their victim. The philosopher in the wind-tossed boat, far from aiming at a Stoic detachment from the crisis, ought to be rightly concerned for the lives of those on board and that emotion ought to lead him to do all he can to save them from the danger.
It is indeed possible to love God with all your heart, as well as all your mind.