Tawheed is the mother of all obligations. Without it, you cannot be a Muslim and all of your good deeds are fruitless. It is vital for one to understand the pillars and conditions of tawheed in order to ensure that he/she is a real Muslim. Failure to fulfil any condition or pillar of tawheed will nullify a person’s Eemaan and Islam, and hence will either be a mushrik or murtad (apostate). The conditions of tawheed are as follows:
1. Al-‘Ilm - Knowledge
Allah (SWT) says in the Qur’aan: “So know that Laa ilaaha ill-Allah (none has the right to be worshipped but Allah)…” (EMQ Muhammad, 47: 19)
If you testify that there is no ilaah worthy of worship and obedience, you must also know and understand all of Allah’s (SWT) attributes and functions or you will become mushrik.
This verse is a decisive request to have knowledge about Allah (SWT). For example, knowing that He is the only Legislator, one will never vote for any kaafir to legislate law. Likewise, by knowing that He is the only Provider, one will never fear poverty.
Having knowledge of tawheed is more vital than studying the Qur’aan, as indicated by the hadeeth of Jundub bin ‘Abdillaah who said: "We used to study Eemaan before we studied the Qur’aan…" (Sunan Ibn Maajah, Kitaab ul-Eemaan no.60), and the Messenger Muhammad (SAW) also said: "The one who dies, knowing (understanding) Laa ilaaha ill-Allah will enter paradise." (Saheeh Muslim, Kitaab ul-Eemaan)
We are obliged to study, learn and know about Allah (SWT); what He likes and dislikes, loves and hates, His names and attributes etc.
You can only testify that which you have knowledge about. Therefore, if someone claims to be a witness, and he is asked about what he has seen, and replies: "I’m not sure", this person is completely daft as he testifies to something which he has no knowledge of. Similar to this person is the one who testifies the Kalimah, yet he does not understand what it means.
Allah (SWT) says: “This (Qur'aan) is a Message for mankind (and a clear proof against them), in order that they may be warned thereby, and that they may know that He is the only One Ilaah (God - Allah) - (none has the right to be worshipped but Allah), and that men of understanding may take heed.” (EMQ Ibraaheem, 14: 52)
2. Al-Yaqeen - Certainty
Knowledge is not enough, as many kuffaar know about Islam but they do not believe in it nor do they have certainty about it. Allah says: “Only those are the believers who have believed in Allah and His Messenger, and afterward doubt not but strive with their wealth and their lives for the cause of Allah...” (EMQ Hujaraat, 49: 15), and the Messenger Muhammad (SAW) said: "Whoever testifies that there is no god worthy of worship and obedience but Allah and that I am the Messenger of Allah, without any doubt he will enter Jannah." (Saheeh Muslim)
3. Al-Qubool - Acceptance
After having knowledge and certainty, you MUST accept. Some people may believe, have knowledge, and have certainty, but may not accept, as it may be too difficult for him or he may not accept out of his own personal desires. Allah (SWT) says: “Truly, when it was said to them: ‘Laa ilaaha ill-Allah (none has the right to be worshipped but Allah)’ they puffed themselves up with pride (i.e. denied it).” (EMQ as-Saaffaat, 37: 35)
4. Al-Inqiyaad - Submission
Allah (SWT) says: “But nay, by your Lord, they can have no Eemaan, until they make you (Muhammad [SAW]) judge in all disputes between them, and find in themselves no resistance against your decisions, and accept (them) with full submission.” (EMQ an-Nisaa’, 4: 65)
Allah (SWT) describes those who do not submit to Him as disbelievers, and swears to this by Himself. Having knowledge, certainty and acceptance is not enough; you must also have submission with no haraj (discontent). You must submit to Allah, and all His names and attributes. Allah (SWT) also says: “There is no compulsion in the religion. Verily, the right path has become distinct from the wrong path. Whoever disbelieves in Taaghout and believes in Allah, then he has grasped the most trustworthy handhold that will never break (i.e. he will have submission). And Allah is All-Hearer, All-Knower.” (EMQ al-Baqarah, 2: 256)
And also: “The command (or the judgement) is for none but Allah. He has commanded that you worship none but Him (i.e. His Monotheism), that is the (true) straight religion, but most men know not.” (EMQ Yoosuf, 12: 40)
Thus, He (SWT) orders us to worship and submit to none but Him.
5. As-Sidq - Believing
Allah says: “When the hypocrites come to you (SAW), they say: 'We bear witness that you are indeed the Messenger of Allah.' Allah knows that you are indeed His Messenger and Allah bears witness that the hypocrites are liars indeed.” (EMQ al-Munaafiqoon, 63: 1)
Allah testifies that the Munaafiqoon are liars as they claim to be Muslims but they do not believe. Thus, believing is a condition of Tawheed as Allah (SWT) also says: “And of mankind, there are some (hypocrites) who say: 'We believe in Allah and the Last Day', while in fact they believe not.” (EMQ al-Baqarah, 2: 8)
Allah testifies again that they are not believers as they never have Eemaan in their hearts. The munaafiq has no talaazum (moulding) between his inner and outer as he shows Islam but conceals kufr. The Messenger Muhammad (SAW) said: "The one who testifies ‘There is no God worthy of worship but Allah’, (whilst sincerely) believing in the heart; Allah will forbid him from the Hell-fire." (Al-Bukhaari, Kitaab ul-‘Ilm no.128 and Muslim)
Therefore, the one who does not believe in his heart has the attribute of a munaafiq or kaafir.
6. Al-Ikhlaas - Sincerity
Allah says: “And they were commanded not, but that they should sincerely (with Ikhlaas) worship Allah, and worship none but Him Alone (abstaining from ascribing partners to Him), and perform As-Salaat and give Zakaat: and that is the right religion.” (EMQ al-Bayyinah, 98: 5)
The Messenger Muhammad (SAW) said: "The one who says ‘there is none worthy of worship but Allah and Muhammad is the Messenger of Allah’ seeking sincerely to see the face of Allah, Allah will forbid him from Hell-fire." (Al-Bukhaari and Muslim)
And also, Abu Hurayrah (RA) asked the Messenger Muhammad (SAW): "who is the luckiest person to receive your intercession?" He said: "the one who says Laa ilaaha ill-Allah sincerely from his heart.’ (Al-Bukhaari)
7. Al-Mahabbah - Love
After having knowledge, certainty, acceptance, submission, belief and sincerity; you must also love those whom Allah (SWT) tells you to love, and hate those whom He tells you to hate.
Allah says: “And of mankind are some who take (for worship) others besides Allah as rivals (to Allah). They love them as they love Allah. But those who believe love Allah more (than anything else). If only those who do wrong could see, when they will see the torment, all power belongs to Allah and that Allah is severe in punishment.” (EMQ al-Baqarah, 2: 165)
The Messenger Muhammad (SAW) also said: "The most powerful knot of Eemaan is to love for the sake of Allah and to hate for the sake of Allah." (Ahmad, Aadaab us-Suhbah)
Therefore you must love the Muslims, believers and mujaahideen, and hate the kuffaar, Shaytaan and all other disbelievers; otherwise you will be violating one of the conditions of tawheed and hence become mushrik