Commonly, non-Muslims fail to understand the role of these important concepts in Islam. Islam has been accused of being very legalistic, without much concern for spiritual matters.

Some Christians have said that Islam teaches that we can earn forgiveness by our actions. So, when they compare Islam to their concept of the Messiah dying for human forgiveness, they see Islam as inferior.

In fact, Islam teaches that there can be no forgiveness except through Allah's (God's) mercy. 

Muhammad said "No one will attain salvation by virtue of his actions."

the people asked, "not even you, Messenger of Allah?" He said "Not even me, unless Allah covers me with His mercy and blessings."

A person must repent to Allah, asking for His forgiveness, knowing all the while that it is only by Allah's grace that he may be guided to the truth and so, be successful. He is filled with gratitude and love for his Lord and so becomes closer to and loved by his Lord. He is in awe of Allah's mercy, which is greater by far than the mercy a mother has for her child. Allah even shows mercy to those who disbelieve in Him and hate Him and have no gratitude for all that he gives them, yet he still continues to sustain them. They have much pleasure in this life, but in the next they will be the losers.

"And of mankind are some who take others besides Allah as rivals (to Allah). They love them as they love Allah, but the believers are love Allah more. If only those wrongdoers could see, when they see the torment, that all power belongs to Allah and that Allah is severe in punishment." (Quran chapter 2, verse 165)

"If you love Allah, then follow me ( Muhammad ), Allah will love you and forgive your sins. Allah is oft-forgiving, Most Merciful." (Quran chapter 3, verse 31)

It was reported that The Prophet stayed up all night, standing until his feet became swollen. When he was asked "Why are you doing this, when Allah has forgiven all your past and future wrong actions?" he replied, "Should I not be a grateful worshipper?"

A Muslim's following of the Shariah is not merely like a worker working to earn their wage. Rather, it is an expression of his love and gratitude for Allah, and it stems from his trust in Allah's solutions being the best way to solve his problems.

"And march forth to forgiveness from your Lord and to paradise as wide as the heavens and the earth, prepared for the pious." (Quran chapter 3, verse 133)