Back in 1952 Bill Bright wrote a booklet entitled, "The Four Spiritual Laws." Most everyone from my era was familiar with the tract. In fact, the phrase "God loves you and has a wonderful plan for your life" is one we all know and comes straight from Law 1. Nice. Included in the booklet was a famous train illustration. The engine was marked "Fact", the coal car was "Faith", and the caboose was "Feelings". The point was to tell new believers not to rely on feelings ("Do I feel saved?"), but to trust God's promises. And I have remembered that little train all my life.
You see, we are commanded to do things in the Bible that are, by standard usage, feelings. We are commanded to rejoice, to be thankful, to love, all these kinds of things. We recognize these things as feelings. So how do you command feelings? Well, clearly, the Bible isn't telling us "Feel this way." It isn't rational. So clearly there is a choice element to things like gratitude and love. Conversely, if we limit these terms to their emotional content, we are missing out on the biblical sense of these kinds of commands.
There is, however, a reverse problem. It is a problem that plagues me, so I'm well aware of it. In the train illustration, the booklet says, "The train will run with or without a caboose. However, it would be useless to attempt to pull the train by the caboose." The tendency, if we admit that these types of commands that are generally seen as feelings are actually choices, is to seek a divorce. It goes something like this. "Fine. Love is not a warm feeling of affection, but a choice I make to treat someone well. I am commanded to love my wife. Therefore, I will choose to treat my wife well even though I have no feelings towards my wife." The feelings-based believer would cry "Foul!", but the choice-based believer would have to admit that it makes sense. The feelings-based believer, on the other hand, would be at a loss to help the poor fellow who has no feelings toward his wife. So it would seem to have merit.
Here's the problem. Given the train illustration, you cannot eliminate any component of that train and make it viable. No engine and it goes nowhere. No coal car and it has no fuel. No caboose and it's a meaningless train. It's true that "The train will run with or without a caboose", but what's the point of such a train? It needs all three components. Thus we read Jesus saying, "These people honor Me with their lips, but their hearts are far from Me" (Matt 15:8). It is possible to choose to do what is right without feeling anything and it doesn't work. What God demands is a "whole heart". "I give thanks to You, O Lord my God, with my whole heart, and I will glorify Your name forever" (Psa 86:12). We are designed to long for God, not merely obey Him. "As a deer pants for flowing streams, so pants my soul for You, O God" (Psa 42:1). He is to be our true affection. "One thing have I desired of the LORD, that will I seek after: that I may dwell in the house of the LORD all the days of my life, to gaze upon the beauty of the LORD and to inquire in His temple" (Psa 27:4).
It is true that our faith is based on fact. It is true that the truth is the "engine" that motivates us. It is true that biblically-commanded emotions have a component of choice. What is not true is that emotion plays no significant part in Christianity. We are commanded to feel certain ways towards God and others. That happens by choice. But choice based on fact via faith necessarily produces emotional response. You see, if you can spend time in the presence of God and not feel anything, you didn't spend time in the presence of God. If you can truly love your spouse and not feel anything, you haven't truly loved your spouse. If you don't have an emotional response to the truth of God, you haven't yet apprehended the truth of God. Feelings don't determine facts, but faith based on the truth must produce feelings or you haven't been there yet.