After I posted the 'Right Thigh', the LORD then asked me to look at SHIRK. When I was a child I remember adults saying 'No shirking' and it basically means 'Don't be idle', 'Do your duty', 'Keep working', Keep your agreements' etc.
However, in Islam the 'SHIRK' is a religious doctrine, and it as a very surprising turnaround. The word generally means 'to share' and it is used in particular to do with having a relationship or establishing a partnership.
Simply put within Islam 'SHIRK?' is an unforgivable crime. 'God may forgive any sin except for committing shirk'. 
In the bible, the only act unforgivable is standing against the Holy Spirit. Without getting heavily into all of the Islamic scriptures and texts, let us simplify it, and outline what this really means in terms of spiritual growth and development. What does Islam forbid Muslims to do?
1. Have a relationship with God.
2. Have a sacred union with God.
3. Have any contact with the Holy Spirit in any form.
4. Share sacred divine experiences.
5. Share a sacred relationship with a partner.
6. Exalt children as sacred and heavenly.
7. Experience the many heavens.
8. Experience the Son of God for themselves.
9. Develop spiritually and claim their right to be sacred and heavenly.
This then results in the fact, that Muslims can never ever do the will of the LORD God, if they're not allowed to have a relationship with him, and Islam forbids exactly that.
Last but not least, 'Nowhere the Arabic word for religion (muzdhab) is found in the Koran; Instead, al-Din or deen al-Haq (The Righteous Path).' The word religion does not exist in Hebrew either and the righteous path is to do with the highway of holiness. The path of the healers. What does God call for in the bible? His healers.
As the Son of God said 'Narrow is the gate and very few find it'.