Traditional Iranian ceremonies always was a great part of our society (at least as far as I can remember , and note that these ceremonies are not approved by Islam most of the time but people kept doing them after revolution).But nationalism became regular part in recent years.I don't think it is dominant part , as far as I see it is important part.

I should mention in recent years Iran became so much wired country in cultural sense. at one side of spectrum we have people who hate religion, at the other side we have people just like Al-Qaeda , but Shia version which are so small in compare the other part , but they have secret regime support)

But despite of regime multi-billion $ media funding and propaganda most people does believe in secularism. and this is the most serious (by far) dead end for this regime will counter in next 20 years.most of people in Iran knows that, regime needs an imaginary enemy. who is better than US, the supporter of Israel (which they believe is root of all evils).by bombing them you just gave them a reason to deceive more people.Give them internet,twitter, porn , facebook,gay tv shows, game of throne, friends tv shows and etc and you will see collapse of regime much much sooner than you can even imagine)

The distance young generation have with religion is far far than most of people outside of Iran can imagine.Despite of 5-6% of hardliners and 25-35% people who make living inside/because of government,in recent years most of people became or atheist or with some kind of their own religion. Majority of young people proud about pre-Islamic history.(personally I don't know about that area and I don't have opinion)

By their "own religion" I mean secular religion, They believe in separation of religion and government at same time they believe on Islam.(some kind of old fashion Shia, before khomeini). At the other hand , we are having (or generating) serious hard liner in other side. People who hates religious, people who hate Islam.(you can search about Shahin Najafi , A singer who sentenced to death by Mullahs like Salman Rushdie)

In Iran despite of west media propaganda you can have every Idea you want in private and most of the time government will not hurt you if you pretend you are normal person in their definition.(You can be an alcoholic , You can be gay) BUT the serious issue here is ,the cost of doing anything other than regime says in PUBLIC is so so so high (most of the time death), and because of that people are afraid of make public their own identity. Just look at the page "My Stealthy Freedom" in facebook.Just imagine the level of government aggressiveness.Taking picture without scarf becomes heroic act here(just imagine , ridiculous thing like this is punishable).Because of this regime. But about saudi arabia , I can assure you Iranian people are far far secular than people at countries like saudi arabia.I can even claim they are secular than Turkye people. Last friday was a demonstration about Israel.The city I live in with population of 2 Million.They only managed to bring ~50,000.Thats all.This is serious defeat for this regime.Because this demonstration is so important for them (all ideology of regime hinges on resistance against US and Israel and for demonstration for showing this , only 1/40 come with all the money the spent).Every Military person have to participate,most of people works for non-military part of regime should too.But that's all , 50 thousands for 2M city.(the important fact here is everybody who believe in regime politic will come to these demonstration , because these are so important for them)

The main problem here is in Iran we have a people-government spectrum , and they both are at other side. One is really aggressive and religious and the other side we have majority people with believe in freedom-secularism. The majority of ordinary and non-educated in people do not believe in religious-regime.