It is not enough that one merely utter the Shahadah for it to be accepted by Allah. It is the key to the gates of Paradise, but in order for it to work, it needs to have the right ridges.
The Shahadah must meet the following conditions for it to be accepted by Allah:
One must have knowledge that all other deities worshipped besides Allah are false, so there is no deity worshipped in truth except Allah. Never should anyone else be worshipped, even if he be a prophet, a messenger or an angel. Allah is the only one who deserves all types worship, such as salah (prayer), du`aa’ (supplication), hope, sacrificial slaughtering, making oaths, etc.
Whoever directs any type of worship to other than Allah has committed kufr (disbelief), even if he uttered the Shahadah.
One must have certainty in the Shahadah. Certainty is the opposite of doubt, so there is no room for a person to doubt or waver in his belief. Allah says:
The believers are only those who have believed in Allah and His Messenger, and afterward doubt not, and strive with their wealth and their lives for the Cause of Allah. Those! They are the truthful. (Al-Hujurat 49:15)
One should accept the Shahadah fully and not reject it. It is not sufficient that a person merely know what the Shahadah means and believe it with certainty. Rather he must accept it my pronouncing it openly and accepting to become a Muslim. Allah says:
Truly, when it was said to them, “La ilaha illa Allah (no deity is worshipped in truth except Allah),” they puff themselves up with pride and deny it. (As-Saffat 37:35)
It means obedience and acting upon all what the Shahadah necessitates.
A person must do according to what Allah ordered and abstain from what He prohibited. Allah, Exalted be He, says:
And whosoever submits his face to Allah, while he is a muhsin (doer of good), then he has grasped the most trustworthy handhold [La ilaha ill-Allah]. And to Allah return all matters for decision. (Luqman 31:22)
We should note that the word “muhsin” in the verse literally means a person who does something well. Here it means one who does righteous deeds sincerely for Allah, according to the method the Prophet (peace be upon him) taught us.
Here we see that Allah mentions both submission to Allah along with doing righteous deeds, and only if a person does this has he grasped onto the sure handhold of the Shahadah.
One must be truthful in his Shahadah. Even though a person may be doing all these things on the outside, he might be hiding disbelief in his heart, like the hypocrites.
They say with their tongues what is not in their hearts. (Al-Fath 48:11)
6- Sincerity of worship
One must make his worship and obedience sincerely for Allah alone. And it may be that one fulfills all the previous conditions, but he directs worship to other than Allah at times, like supplicating to the dead, etc. He has not made his worship purely for Allah.
And they were not commanded except to worship Allah, following the religion purely and sincerely for Him, turning away from other religions. (Al-Bayyinah 98:5)
One must love Allah, His Messenger, and His righteous slaves. He must hate and show enmity towards all who show enmity to Allah and His Messenger. He must prefer what Allah and His Messenger love, even if it is different to what he desires. Allah says:
Say: If your fathers, your sons, your brothers, your wives, your kindred, the wealth that you have gained, the commerce in which you fear a decline, and the dwellings in which you delight… are dearer to you than Allah and His Messenger, and fighting in His Cause, then wait until Allah brings about His Decision (torment). And Allah guides not the rebellious and disobedient to Allah. (At-Tawbah 9:24)
Shahadah & Oneness
The Shahadah also necessitates that Allah is the only one who has the right to legislate, whether it be in matters concerning worship, or matters concerning the government of human relations in both the individual and public affairs. The act of making something prohibited or lawful is for Allah alone. His Messenger merely explained and clarified Allah’s commandments.
And whatsoever the Messenger gives you, take it, and whatsoever he forbids you, abstain (from it). (Al-Hashr 59:7)
The article is an excerpt from”How to Become a Muslim” by Abdul-Rahman Al Sheha.