Many people have made a distinction between head knowledge and heart knowledge. Head knowledge is typically seen as an impersonalized knowledge of facts, information, figures, etc. Whereas heart knowledge is generally seen as something a person feels and reacts to. Who decided to separate the two? I contend that head knowledge is heart knowledge and vice versa.
Knowing About A Topic
It is possible to know many things about a topic with your head; however, your heart will always feel something as to what you have learned. My brain tends to forget or lock away the things that I don’t care about with my heart or are unimportant to me (i.e. math, science, etc.). I know lots of things about lots of topics, but my heart races for the ones that I actually care about knowing (i.e. theology, apologetics, history, understanding culture, etc.)
There comes a point where your heart is changed by what you know about a topic. Either your heart feels positive, negative, or apathetic feelings towards the “head knowledge.” Nevertheless, heart knowledge follows from the head knowledge. The more we know about a topic, the more we are able to be enthralled by it. Generally, it is harder to retain knowledge about topics that we don’t necessarily care for or show interest in.
Heart knowledge doesn’t always have to be positive feelings towards a topic, it merely has to be any feeling at all. As mentioned you may learn much about something and find that it caused your heart to love it. Additionally, learning more about a topic may make you feel negative towards that topic because of what you learned about it. Other times, you may be faced with knowledge that you’re simply apathetic towards and your heart doesn’t really care about the knowledge taken in by your head. Sometimes limited knowledge of a topic might make us feel in such a way that we might not otherwise have felt if we had more head knowledge (ex. anger before we have all the facts, etc.)
My point here is that the two are inseparable. What you learn with your head will always lead to what you feel in your heart. So when some accuse others of “knowing something with their head but not their heart,” this is a slightly misleading statement as it is a near impossibility to accomplish knowledge of one without the other.
If we want to love God with our hearts, we need to know Him with our minds like we know no other topic. I have heard John Piper say that the way to stir affections in your heart towards God is to read a systematic theology book because what you are learning in your mind invariably works itself out in your heart.
Jesus said to “love the Lord your God with all your heart and with all your soul and with all your strength and with all your mind” (Matthew 22:37; Mark 12:30; Luke 10:27). This has historically raised the question in people’s minds if the heart, soul, mind, and strength are separate entities or are they all one cohesive unit? Whatever conclusion one comes to about the matter, it is still vitally important to remember that we are to love God with our heart/soul/mind/strength. The heart knowledge & head knowledge, again, work together for the common purpose of loving & glorifying God.
Charles Haddon Spurgeon was one who understood the relation between the head & the heart well when he wrote “Around The Wicket Gate.” Here are some points made:
- If you want to believe in Jesus, hear about him, read about him, think about him, know about him, and so you will find faith springing up in your heart. 
- If hearing and reading suffice not, then deliberately set your mind to work to overhaul the matter [emphasis in the original], and have it out. Either believe, or know the reason why you do not believe. See the matter through to the utmost of your ability, and pray God to help you to make a thorough investigation, and to come to an honest decision one way or the other. Consider who Jesus was, and whether the constitution of his person does not entitle him to confidence. Consider what he did, and whether this also must not be good ground for trust. Consider him as dying, rising from the dead, ascending, and ever living to intercede for transgressors; and see whether this does not entitle him to be relied on by you. 
- At one time I might have needed evidence to make me believe in the Lord Jesus; but now I know him so well, by proving him, that I should need a very great deal of evidence to make me doubt him. It is now more natural to me to trust than to disbelieve: this is the new nature triumphing; it was not so at the first. The novelty of faith is, in the beginning, a source of weakness; but act after act of trusting turns faith into a habit. Experience brings to faith strong confirmation. [45-46]
- When you intelligently trust in Jesus as having suffered for you, then you discover the fact that God will never punish you for the same offense for which Jesus died. 
- The fact is, that we most of usknow quite enough already, and the real want with us is not light in the head, but truth in the heart. 
There is no heart knowledge without head knowledge. There is no head knowledge without heart knowledge. Heart knowledge is head knowledge. What we know about a topic is the foundational roots of what we feel about a topic. The two are inextricably linked together and we ought not accuse someone of lacking one or the other simply because they don’t feel what they ought to feel about that head knowledge.
– Tyson Bradley
John Piper – Think: The Life of the Mind and the Love of God
J.I. Packer – Knowing God