Do you love Crispus Maximus?
You can't say. You don't know who that is. . . .
To love someone you must know them or know something about them. Some say "doctrine divides" and "theology is what men have come up with. I just love Jesus. . . ."
Which is foolishness. How can you love someone if you don't know who they are and what they are about? "Well, He's in my heart, that's how I know Him!"
""The heart is deceitful above all things; and is desperately wicked. Who can know it?" --Jer. 17:9
What many who claim from ignorance to "love Jesus in my heart" are actually loving is the idol they have made for themselves to serve.
"My people are destroyed for lack of knowledge; because you have rejected knowledge, I reject you from being a priest to me." --Hos. 4:6
Yes, we have a relationship with the Lord within, and His Spirit dwells in our hearts through faith (Eph. 3:17) but in order to discern (which we are commanded to do!--Cor. 2:15) what is of God and what is not--as in, what comes from Truth versus what comes from our asserted idol--we must be like "good Bereans" and go to The Word to test it.
The Bereans "were more noble-minded . . . for they received the Word with great eagerness, examining the Scriptures daily to see whether these things were so." --Acts 17:11
Having "eagerness" to examine the Scriptures is a sign and fruit of having the Spirit. It is also a sure way to drift from the Spirit and be caught by the empty distractions of the world when one moves along seemingly content with a sort of vague assent to "being a Christian", claiming to "love Jesus" but doing little more than that toward Him. Where is our attention? The one you love is on your mind constantly. All you do and live for is in reference to them.
But instead, what people do most of the time and what they live for . . . is about themselves and the idol (again, just another version of their self) they have made in His place.
Theology ("the study of God and God's relation to the world") and doctrine revealed by God's Word are voraciously sought with "eagerness" by the disciple who wants to gain more knowledge about the One they love. Generally when you love someone or something you want to learn all you can about them or it. People have various hobbies, obsessions, interests . . . and they can tell you all about them. Comic books, politics, dog breeds, guns, gardening. . . . Look at the time, effort and money spent on these things for the one who would specialize in such.
Yet God--the One who is responsible for our very existence, character, possessions, talents, breath . . . rates barely a thought day to day.
It would be one thing if He were utterly mysterious, where we had no information or knowledge of Him and His ways. But this is not the case! The very Creator of the universe and all that is--He Who was . . . and is . . . and is to come--gave us His written Word . . . which seems to be endlessly explorable while simultaneously sure and fast on the essentials, to guide us and against which we are able to test that "Jesus in my heart". . . .
"But examine everything carefully; hold fast to that which is good. . . ." --1 Thess. 5:21
"Be diligent to present yourself approved to God as a workman who does not need to be ashamed, accurately handling the word of truth." --2 Tim. 2:15