Love is the source of loyalty and hate is the source of opposition; it is by this that both the heart and the hand are moved to act. Love inspires intimacy, concern and help; hate provokes obstruction, enmity and rejection. Love and hate are both related to the declaration of faith and constitute essential elements in it. The evidence of this from the Qur’an and the Sunnah is considerable.
As for the Qur’an, consider the following ayat:
“Let not the believers take disbelievers for their friends in preference to believers. Whoever does this has no connection with Allah unless you are guarding yourselves against them as a precaution. Allah bids you to beware (only) of Himself. And to Allah is the journeying.” (3:28).
And He says:
“Say, (O Muhammad, to mankind): ‘If you love Allah, follow me; Allah will love you and forgive you your wrong actions. Allah is Forgiving, Compassionate.’ Say: ‘Obey Allah and the Messenger.” And if they turn away, then surely Allah does not love the disbelievers.” (3:31‐32).
Speaking of the aims of the enemies of Allah, He says:
“They long for you to disbelieve even as they disbelieve, so that you may be the same (as them). So do not choose friends from among them until they go out in the way of Allah.” (4:89)
“O you who believe! Do not take the Jews and the Christians for friends. They are friends of one another. And whoever of you takes them for friends is (one) of them. Surely Allah does not guide wrongdoing people.” (5:51)
“O you who believe! Whoever of you becomes a rebel against his deen, (know that in his place) Allah will bring a people whom He loves and who love Him, humble towards the believers, harsh towards the disbelievers, striving in the way of Allah, and not fearing the blame of any blamer” (5:54).
We will mention only a few of the many hadith and reports of the Companions on this subject: Imam Ah‐mad reports from Jarir ibn Abdullah that the Prophet, may Allah bless him and grant him peace, made him swear an oath to ‘offer counsel to every Muslim and to steer clear of every disbeliever.’  Ibn Shayba reports that the Prophet said,
“The strongest bond of faith is love for the sake of Allah and enmity for His sake.” 
Ibn Abbas reports that the Prophet said,
“The strongest bond of faith is loyalty for the sake of Allah and opposition for His sake, love for the sake of Allah and enmity for His sake.” 
Ibn Abbas is also reported to have said,
“Whoever loves for the sake of Allah, and hates for the sake of Allah, and whoever seals a friendship for His sake, or declares an enmity for His sake, will receive, because of this, the protection of Allah. No one may taste true faith except by this, even if his prayers and fasts are many. People have come to build their relationships around the concerns of the world, but it will not benefit them in any way.” 
Shaikh Sulaiman ibn Abdullah ibn Muhammad ibn Abdul Wahhab explained the words of Ibn Abbas by saying that the meaning of ‘to seal a friendship for the sake of Allah’ indicates the obligation of establishing relationships of love and trust for His sake; this is friendship for the sake of Allah. It also indicates that simple affection is not enough here; indeed what is meant is a love based upon alliance. This entails assistance, honour, and respect. It means being with those whom you love both in word and deed.
As for ‘enmity for the sake of Allah’, it includes the obligation to declare enmity for His sake: opposition for the sake of Allah. It is to declare opposition in deed, to take up arms against His enemies, to shun them, and to stay far from them both in word and deed. This proves that simple opposition of the spirit is not enough, and that it must be a complete honouring of your commitment, for Allah says:
“There is a good example for you in Ibrahim and those with him, when they told their people: ‘Surely we disassociate ourselves from you and all that you worship beside Allah. We have done with you. And there has arisen between us and you enmity and hate for ever until you believe in Allah only.” (60:4) 
All this leads us to conclude that loyalty for the sake of Allah really means to love Allah and to come to the assistance of His Deen; it is to love those who are obedient to Him and to come to their help. Opposition for the sake of Allah is to feel anger at the enemies of Allah and to struggle against them. Because of this Allah has called the first group the ‘party of Allah’ and the second the ‘party of Satan’:
“Allah is the Protecting Guardian of those who believe. He brings them out of darkness into light. As for those who disbelieve, their patrons are false deities. They bring them out of light into darkness. Such are rightful owners of the Fire. They will abide therein.” (2:257).
And He says:
“Those who believe do battle for the cause of Allah; and those who disbelieve do battle for the cause of idols. So fight the friends of Satan. Surely Satan’s strategy is always weak.” (4:76).
It is well known that Allah has never sent a Prophet on His mission without also raising up opponents against him. Allah says:
“Thus have We appointed for every prophet an adversary devils from mankind and the jinn who inspire in one another plausible words that are deceiving.” (6:112).
It may be that opponents of Divine Unity possess some learning, a part of Revelation, and proof. As Allah says:
“And when their Messengers brought them clear proofs (of Allah’s Sovereignty), they exulted in the knowledge which they (themselves) possessed. And that which they had become accustomed to mock befell them.” (40:83).
It is the obligation of every Muslim to learn from Allah’s deen whatever may serve as a weapon for him in the struggle against the friends of Satan. In this he should have no fear and no misgivings, since the devil’s strategy is always weak. Allah says:
“And surely that Our host would be the victors.” (37:173).
To the host of Allah shall be the victory in discussion and in debate, as in war and strife. In this way an ordinary man from the party of the One God will overcome a thousand scholars of the disbelievers. 
If the aim of the enemies of Islam, whether they are atheists or Jews, or Christians or modernists, or Zionists or Communists, is the emasculation of the ‘aqeedah of the Muslims, and the erosion of their unique character in order to make them ‘the ass of the chosen people’, (as it is put in ‘The Protocols of the Elders of Zion’), then the urgency of this issue should become clear to every Muslim.
We should all take heed, for ourselves and for those who are with us, so that we may warn all the Muslims who are slipping away into the abyss of apostasy, warn them of the treacherous call of the disbelievers to what they call ‘brotherhood and equality’, warn them of the false claim that religion is for Allah but that nationhood is for the masses. We will return to this point in more detail later.
For the present, the evidence is clear from the Qur’an and the Sunnah that allegiance is demanded by the declaration of faith since this is an essential part of its meaning. As Ibn Taimiya has said,
‘The declaration of faith, “There is no god but Allah”, requires you to love only for the sake of Allah, to hate only for the sake of Allah, to ally yourself only for the sake of Allah, to declare enmity only for the sake of Allah; it requires you to love what Allah loves and to hate what Allah hates.’  It also requires you to ally yourself to the Muslims wherever you find them and to oppose the disbelievers even if they are your closest kin.”
 Imam Ahmad, Musnad, 4/357‐8.
 Abu Bakr Abdullah ibn Muhammad ibn Shaybah (d.235 AH), Kitab al‐Iman.
 AtTabrani, alKabir,
 Ibn Rajab al‐Hanbali, Jami’ al’‐Ulum wa’l‐Hikam, p.30.
 Muhammad ibn Abdul Wahhab, Shark Kitab at‐Tawhid, p.422.
 Abridged from Muhammad ibn Abdul Wahhab, Kashaf ash‐Shubuhat, 3rd edition, p.20
 Ibn Taimiya, al‐Ihtijaj biʹl‐Qadar, p.62.
Taken from the book: Al‐Wala’ wa’l‐Bara’ (Part 1)