Salam Dear Sary,
Thank you for your question and for contacting Ask About Islam.
May Allah reward you for your efforts in da`wah. Just keep in mind that you will be rewarded not according to whether or not your friend accepts Islam, but according to your efforts, for it is only Allah Who opens hearts.
In some ways, Muslims don’t live much differently from non-Muslims. They go to work, shop, play, get married, spend time with family and friends much as anyone else. The differences come in their attitude toward their daily activities.
Dedicated Muslims know that everything they do in conformance to God’s laws is an act of worship that will be rewarded if it is done with the intention of pleasing God. Even having intercourse with one’s spouse will be rewarded.
The most obvious manifestation of Muslims’ belief is the performance of five daily Prayers called salah. Muslims should schedule their activities around the Prayers and also try to keep God in mind throughout the day.
This may be the biggest change in your friend’s lifestyle, as it probably will entail getting up earlier than he is accustomed, finding a place to pray at work, and changing the daily schedule a bit, especially on Fridays when he must attend the congregational Jumu`ah Prayer in a mosque. But the personal relationship with God—with no intermediaries—is all-important and must be begun from the start.
Muslims should also develop their character. They should be kind, generous, honest, trustworthy, and hard-working. Your friend probably has at least some of these qualities already, and he should work on improving himself.
From my own experience, I feel that the main difference between myself and my non-Muslim (Christian) family is our attitude toward God. As a Muslim I recognize God’s majesty and His right to make laws and to be obeyed.
For my family, God is someone they ask help from and someone they worship on Sundays, but His laws don’t really have much place in their lives. For sure, they don’t murder, steal, or cheat; but they accept pre-marital sex and homosexuality as just a part of modern life. “Times change.”
If my experience can be generalized—and for sure there are exceptions on both sides—then if your friend accepts Islam, he should expect to live his life differently because he wants to develop his relationship with God and keep in touch with Him.
A big change for many new Muslims is in how they spend their leisure time. They can’t drink with their old friends, or be around others when they are drinking. So unless their old friends are willing to meet without alcohol, new Muslims are often lonely.
I hope that the mosques near him will have supportive programs for new Muslims to help them make new friends and adjust to the many changes they have to make.
Of course, there will likely be changes in diet. Your friend will have to avoid pork and pork products and any non- halal meat. I’m not a scholar of fiqh, so I won’t try to define halal meat in Europe; there are various opinions on the subject of what exactly is and is not allowed for Muslims. But meat that is slaughtered by Islamic ritual should be widely available in Europe now, I think.
Your friend might also need to change his occupation if it conflicts with Islamic law. For example, Muslims are not only forbidden to drink alcohol, but they are also forbidden to manufacture, distribute, transport, sell, or serve alcohol. There are some occupations that deal with riba (interest) that are forbidden. You can check with our Ask the Scholar section for more on that.
Islam does attempt to deal with all aspects of life, but at the practical level we must realize that that is not always possible today. Many of the laws in Muslim countries conflict with Islamic Law (Shari`ah), and where Muslims are a minority they cannot always apply Shari`ah.
Still, we must strive to live in accordance with God’s laws as best we can. It should remain our ultimate goal as a Muslim Ummah (nation) to establish justice and live by the Shari`ah.
The lives of the Prophet Muhammad (peace be upon him) and his Companions can give us guidance and inspiration, but when questions arise on how to deal with certain situations, Muslims should turn to someone educated in Islamic fiqh(jurisprudence) for answers. There are many books written that discuss the basics of an Islamic society.
I hope this and the provided links answer your question satisfactorily.