In The Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
A non-Muslim can join Muslims in prayer without any reservation as a means to get to know how prayer is properly done.
Responding to your question, the prominent Al-Azhar scholar Sheikh `Abdul-Majeed Subh states the following:
However, my advice to you is not to follow the apparent practices of some Muslims, as Muslims’ practices may be correct or wrong. This depends on their conformity or otherwise with Islamic teachings. You are to depend on reliable Muslim scholars to get reliable knowledge of Islam.
Also, you should depend on the Quran, which is the primary source about Islam. If you can read Arabic you should depend on it, but if you rely solely on translations, then you should choose authorized translations approved by Muslims, as there are erroneous translations that are misleading.
As for prayer ritual, you can join Muslims in prayer without any reservation as a means to get to know how prayer is properly done. If you have any queries do not hesitate to contact us.
Moreover, Dr. Muhammad M. Abu Laylah, Professor of Islamic Studies and Comparative Religions at Al-Azhar University, adds:
As Muslims, we consider you a Muslim by intention. Good intention is a basis in Islam. Islam is a religion for all humanity at large. It is not limited to any particular nation or location or time.
It is always good and highly appreciated by Allah to try your best to know the truth and then to adhere to it.
Allah will definitely help you and guide you to come to the light of Islam. Until you are practically a Muslim, we advise you to practice Islam to the best of your ability.
Don’t worry, as practicing Islam will help you spiritually and psychologically to receive with your heart what you are trying to know about it with your mind.
You can attend prayers at the mosque and visit some Muslims as well. This will put you in the climate of Islam and help you feel it. If you would like to say “La ilah illa Allah” (“There is no god but Allah”) with your heart and tongue, then you are a complete Muslim.
Islam is a very easy and forward religion, though it is very rich and deep. It offers humankind what helps both in this world and in the Hereafter.
Allah Almighty knows best.