Is there any conflict between any two religions such as with one religion saying bad things about the other?
Sadly, there are huge numbers of examples of one religion saying bad things about the other. This does not necessarily mean that all people from one religion are against all people from the other, but we often hear examples of people from one religion criticizing another.
Right here in the United States, we have the example of evangelical Christian criticisms of the Mormon church. Recently, a supporter of Texas Gov. Rick Perry (who is running for president) criticized the Mormon faith, presumably because Mitt Romney, a Mormon, is also running for president. The supporter, a pastor, said that Mormonism is a cult and is not Christian.
The Seventh-Day Adventist Church is also seen by many evangelicals as a cult. In turn, Adventists are very strongly opposed to the Roman Catholic Church. They sometimes call the Church the antichrist and argue that it will help to oppress true believers in the end times.
There are many other possible examples of religions criticizing one another.
It seems to be so because of our ignorence but there lies no difference in the sayings of different religion. I feel almost all religions have lost their true sanctity. There is only one religion named 'SANATANA' denotes universal truth and out of it time to time some great people found out some truth according to their intellect and devotion to the highest authority behind the creation of this universe. When they were there, it worked well because they were there to explain to the people. As time passes, the followers add their own thinking according to their intellect and devotion. Thus it starts mis interpreting the clauses according to their own cause.
If we see, there is no difference in the teaching of various religions but of course there are differences in executing them. Now the people leading them are not like the pioneer of the religions and hence the followers are confused. The present heads of the religions sway their followers to fulfill their desires. They are not perfect.
It is called that Dara, a brother of Aurangajeb, the king of Delhi translated about 52 Upanishads in the vedas. When I talk of the teaching of upanishads without naming them, my students from Muslim community ask me where from I have taken them. They say they have read them in Koran. In Bible also find the same teachings as in the upanishads and these were considered to be written earlier than the Bible and the Koran.
One does not have to look very far to find an example of conflict between religions. Not only does conflict exist between different religions but many times it exists within the same religion. There has been much conflict between Christians and Muslims because of their different faiths. There have also been many conflicts between denominations of the same religion because of various beliefs. Many of these differences do not concern the basic tenants of one's faith, but only details. As long as there are two different relgions, there will be conflict between religious faiths. Some of these conflicts have led to war and hatred between peoples of the world. There have been few successful attempts to reduce religious conflicts. In the United States, one strategy had been to accept all religions and their belief systems in hopes to aviod these types of difficult situations.
Since the foundation of religion, different sects have been fighting and killing eachother "in the name of God". In pagan times, they fought on behalf of their national God while still believing in others. Now in Monotheistic times, when you have Muslims who believe "no god but God" and Christians who fear to worship "any gods but Me", there are obviously going to be some clashes (even though Christians and Muslims most likely worship the same God anyway).
Every religion today believes that they, and not others, possess the true God and abide by the "right" rules in order to get to Heaven, and when they see a religion that practices different customs, they believe they're going to burn in Hell. And when you can envision a whole culture of people burning in Hell, there's little to stop them from criticizing and persecuting them.