Is having the name of Jesus displayed anywhere tantamount to idolatry, or is it a "denominational symbol"? [To clarify, I might ask, "Is the written name of Jesus equal to an idol, if displayed openly?"]
Years ago, I bought a car from a young lady. On the trunk lid of that car was the name of Jesus in script-style writing. It was not within a "fish" symbol, and it did not have a cross or any other symbol -- just the name "Jesus." It is not something I would have put on there, but I have to be completely open and tell you I questioned why I would take it off. I left it on.
A couple of years later, a brother [blood relation] saw it and wrote me a letter saying it was equal to the Pharisees "broadening the phylacteries and enlarging the borders of their garment" (cf. Matthew 23:5). In other words, I was all show with no substance -- a hypocrite. This was said without ever asking me about why it was there or how it came to be there and certainly without any knowledge of my heart. After I gathered my composure [I took several months, to make sure I was calm and reasonable], I confronted his charge and pointed out the unjust judgment he had made, making him more like the Pharisees he so despised.
Unfortunately, instead of addressing the issue, it turned into a personal matter and now the name of Jesus on the trunk lid of a car -- along with any religious message on bumper stickers, t-shirts, hats, etc. -- is, according to him, "a denominational symbol", an "idol", and is [in his mind] sending me to hell. [Let me also point out that this same brother believes one should never pray in public or let anyone see us do good deeds lest we are identified as a "hypocrite" per Matthew 6:1-18.]
Am I missing something? Again, I ask the question, but more directly to the issue at hand: Is it unscriptural to have the name of Jesus on public display or any religious message [namely on t-shirts, bumper stickers, etc.] in the public eye? This seems to me to be a very twisted and narrow view of things and would require us -- if we are going to be consistent -- to take the title of Jesus off of our signs out front of the church buildings ["Church of ..."], cease handing out tracts and other publications promoting the one true faith, and other ridiculous extremes.
This is not about the "fish" symbol, wearing a cross, or any other religious symbol. I did not even try to defend those things and I believe it is a different matter entirely. This is about the name of Jesus.
Idolatry is the worship of anything that is not God. The form of worship is always a matter of discussion. Colossians 3:5 goes so far as to say that greed is a form of idolatry. If you think about the consequences of that, the definition of worship becomes rather loose. I think the best way to describe worship given that context is "anything that you turn to for guidance and security." That type of definition won't satisfy Webster, but it helps understand how greed could become a type of idolatry.
Idolatry is often a matter of how something is used rather than the object itself. Consider Moses' bronze snake. In Numbers 21:8-9 it says, "The LORD said to Moses, 'Make a snake and put it up on a pole; anyone who is bitten can look at it and live.' So Moses made a bronze snake and put it up on a pole. Then when anyone was bitten by a snake and looked at the bronze snake, he lived." A few hundred years later Hezekiah is commended for destroying the snake in 2 Kings 18:4 where it says, "He removed the high places, smashed the sacred stones and cut down the Asherah poles. He broke into pieces the bronze snake Moses had made, for up to that time the Israelites had been burning incense to it. (It was called Nehushtan.)" It was the exact same figure that went from being something that God commanded to an idol that led people astray.
Now consider some things that men use in their devotion to God. For discussion purposes, I would like to propose looking at various forms of "Christian" (used very loosely here) art. There are statues, crucifixes, paintings, stained glass, jewelry, and little fish symbols. I should point out that none of these come from the Bible because they are never commanded and no one is mentioned as using anything like them. If I look at a painting of someone being crucified, how would I know that it was Jesus in the painting? No one who saw Jesus ever recorded what he looked like. And Josephus mentions that the Romans used crucifixion rather frequently. I would assume that Jesus looked like a typical Israelite and not much like the typical painting that makes him look more middle European. Since I am biased that way, I can look at some artwork and admire the artist's skill and never associate it with Jesus. The painting, by itself, means nothing. It is only when people ascribe something more to it, that there becomes a problem.
If my intention is to remind others of who Jesus was and what he did, then the statue is just a statue that is intended to inspire. However, if people start to turn to it and do something that would show devotion to that object, then there is a problem. One that I notice are little silver crucifixes that women wear around their necks. I have met several who claim that the only purpose of the symbol is to help them "witness" to others. They claim it is there as an open proclamation to others that they are a Christian. However, I have also noticed that these same people, when confronted with a stressful situation, will grab the crucifix as they pray. If they are grabbing it to pray, does that not imply that they ascribe some power to it?
Of course, there are many who bow to the supposed statues of Jesus, kiss his toe, set up statues around their yard or fields to bring "good fortune" to the property, and still try to claim that there is no special significance to the statue. But any act of reverence to an inanimate object means that you ascribe some sort of power to that object. That would include paintings that you might "cross yourself" for or stained glass that you bow before to pray because it makes you feel closer to God. It could even include a church building that you seek out when there is a local disaster because you feel that it is safer because it has the protection of God.
So if you are looking at a bumper sticker that says "Jesus", "John 3:16", "the Word", "Read your Bible" or any of thousands of possible messages, I would have to look at your motivation. Is it there because it is a convenient place to advertise or do you believe that it will help protect you from accidents and road rage? If the latter, then you have ascribed power to the sticker and it has become an idol. If not, then it is what it seems to be -- a billboard. I would remind any naysayers that it was Jesus who said in John 7:24 "Stop judging by mere appearances, and make a right judgment."
Now as a matter of principle, I would also consider Romans 14:13, "Therefore let us stop passing judgment on one another. Instead, make up your mind not to put any stumbling block or obstacle in your brother's way." Also Romans 14:19-21 where it says, "Let us therefore make every effort to do what leads to peace and to mutual edification. Do not destroy the work of God for the sake of food. All food is clean, but it is wrong for a man to eat anything that causes someone else to stumble. It is better not to eat meat or drink wine or to do anything else that will cause your brother to fall." It is obviously bothering your brother and causing him angst. There would be nothing wrong with taking it off so that peace might reign.
As for your brother's charges, you have summarized it well. Yes, there are people who take a passage like Matthew 23, where Jesus was condemning the Pharisee's for their attitude and try to get the passage to condemn their actions. For example, Matthew 23:23 says, "Woe to you, teachers of the law and Pharisees, you hypocrites! You give a tenth of your spices—mint, dill and cummin. But you have neglected the more important matters of the law—justice, mercy and faithfulness. You should have practiced the latter, without neglecting the former." Jesus specifically told them that they were supposed to continue in giving their tenth. It was their attitude that was the problem because they were not interested in the parts of the law that required that they be kind people.
The same can be said about Matthew 23:5. "Everything they do is done for men to see: They make their phylacteries wide and the tassels on their garments long" I don't think that you can get from this passage that Jesus was concerned with a fashion trend. He was concerned about the attitude that was behind the object. If a man bought a coat that just happened to have long tassels, would he have been condemned with the Pharisees? What if the fall fashions that year were long tassels and you could not get a short tasseled coat no matter what you tried? Was Jesus concerned that tassels were getting too long? No, he was concerned that they were using religious actions to demonstrate to the world just how pious they are.
Avoiding hypocrisy is not a matter of hiding all your actions from the world, it is a matter of not doing things in order to be seen. I can put my contribution in the collection plate on Sunday and at a minimum, I know that the treasurer knows how much I put in. The fact that someone happens to know does not negate the gift. However, if I did it for the purpose of being seen, then there is a problem.
Is it possible that someone could put a "Jesus" bumper sticker on their car so that all the world will "know that they are a Christian"? I am certain of it. Does it mean that you have that attitude? No. However, I would use your brother's poorly worded chastisement as an opportunity to check your own attitude. Ultimately it does not matter what he thinks, only what Jesus knows. If there is even a small possibility that he is right and you do keep it there so that people will know that you are a Christian, then it might be a good thing to take it off. Ultimately you are the only one that can judge that.