Thank you for your question and for contacting Ask About Islam.
First, let me start by saying that in modern times Shariah was inaccurately translated as “Islamic Law”. This portrayed Shariah as merely a collection of laws and regulations. Perceiving Shariah as such has produced great confusion in regards to its importance in Islam.
The importance of Shariah can be seen through the meaning of the concept. The word shariah literally means a waterway that leads to a main stream, a drinking place, and a road or the right path. From this meaning, the word shariah was used to refer to a path or a passage that leads to an intended place, or to a certain goal.
The importance of Shariah is evident in the denotations of the literal meaning. Water is life for everything, Shariah is life for the Muslims’ souls and a way of life for them.
On the other hand, Shariah, conceptually, refers to a set of rules, regulations, teachings, and values governing the lives of Muslims. However, these rules and regulations, contrary to how they are often described by many non-Muslims, cover every aspect of life. Shariah embraces worship, morals and conduct, as well as it embraces the political, social and economic, as well as other spheres.
Muslims believe that the purpose of their creation is nothing but servitude [being servants to the creator of mankind]. They also believe that without the guidance of Allah (God) no one will meet this purpose. Therefore Allah sent messengers and prophets with teachings, values, rules and regulations to guide mankind to His way, the right way.
The first step in the fulfillment of the servitude mission is the complete submission to Allah, which is Islam. The second step is following the guidance of Allah, which is the Shariah. In other words, accepting Islam as a religion and the adherence to the Shariah as the guidance.
Hence, the importance of the Shariah is its central role in guiding Man to the right way, whereby the mission of creation can be fulfilled. The Shariah, therefore, is a path - set by Allah for those who accept Him - to follow, in order to attain success both in the worldly life and in the hereafter.
Thus, to live in Islam is to live according to the Shariah, and ignoring the Shariah or even any part of it, deliberately, is ignoring Islam itself. Muslims have to adhere to the Shariah and observe its teachings throughout their lives.
In regards to the second part of your question, concerning the Shariah’s adaptation to new situations, this particular issue is related to a major characteristic of Islam, which is its validity in every time and space. This characteristic is due to the fact that Islam is the final message and Prophet Muhammad, peace and blessings be upon him, is the seal of prophethood. Thus, in order to guide mankind to the path of Allah, the Shariah has to be applicable in every place and in every time.
Many non-Muslims, however, think that the Shariah is mainly a collection of fixed ancient laws that belong to a time other than ours. On the contrary, Muslim scholars agreed on the fact that applying the Shariah requires two essential types of understanding. These two types are; understanding the sources from which the rules are derived, the Quran and the Sunnah (the traditions of the prophet), and understanding the reality in which these rules are applicable. Hence, the application of the Shariah is not in a vacuum; rather it is in a reality that is changeable due to time and space.
Of course Allah knows the best.
Thank you again for your question and please keep in touch.