These kinds of views come mostly from misconceptions and a profound misunderstanding of both religions and of history. Most of the practices that may inspire these types of stereotypes are not truly religious in nature but have their origins in traditions of the different cultures. In fact, both religions share much in common, due to their shared background in the prophets of the Old Testament.
Many of the sayings of the Prophet Muhammad are remarkably similar to those of the Apostle Paul. In both religions the importance of faith is continually exalted. It is not enough to do good deeds, these must be backed by faith. Equal in importance to both religions is the concept of love and loving one's neighbor. They are even similar in the urging to strive to love and forgive one's enemies. The notion of love is also extremely important in the fact that God's love is the cornerstone of both religions. Both religions also urge their followers to devoted their whole lives and their whole being to God and to his service.
Paradise is also a concept that is common to both religions. In both religions the concept of who will be admitted into paradise is a subject of much discussion. Perhaps it is possible to achieve salvation by doing good deeds, or perhaps the way to paradise lies only in being of one or the other religion. Even then, in both religions Paradise exists and is a gift that God, in his mercy, gives to humanity.
What is the reason behind the great misunderstandings that dominate interfaith dialog? This is question about which whole volumes may be written. There is one particular cause though that may be particularly to blame, the way the different aspects of the religion are weighted as well as the way the concepts of the different religions are expressed and articulated. In Christianity the main emphasis is on faith, on believing righteously. Meanwhile, Muslims place a great deal of emphasis on the actions of each individual, on acting in a righteous manner.
Because of this emphasis on action and good deeds, Christians tend to think that Islam is focused on an individuals actions rather than its faith. Trying to reach salvation through works without belief is completely opposed to Christianity (and Islam as well.) Another thing that contributes to this vision of Muslims as focused on superficial aspects rather than on profound internal matters like faith is the way that Muslims follow the example of the prophet Muhammad. What many Christians fail to realize is that in Islam good deeds are useless without faith in God, without the surrendering of oneself to God. Following the example of the prophet Muhammad is not based on some compulsion to follow particular rules or laws but because his example is a way for Muslims to integrate Islam and faith in God into their lives in a practical way.
It is strange that both religions have many of the same concepts, often completely identical, but with different emphasis on different aspects of these. Another aspect that has contributed to this misunderstanding of the common ground that exists between the different religions is the way the information about one is relayed to the other in the media. While the news of the past decade have been dominated by Muslim extremists and terrorists (that have absolutely nothing to do with true Islam) and by the continual armed conflicts in the Middle East, Muslims too have seen the Western religions