It is not implying that Muslims who practice some amount Salafiyyah are not believers, not at all, so long as they believe in what God sent down.

However, if their entire Submission To God is based purely on Predecessor Following then they are of course not believers and just following their predecessors, the same as the disbelievers in the time of The Messengers.

There are undoubtedly Muslims today who practice Predecessor Following which is sometimes referred to as: following a Madhhab, following a knowledgeable person, blindfollowing, following a sect or openly calling it following predecessors (Salafiyyah).

All of this is prohibited in Islām and is the way of the disbelievers that The Prophets and Messengers were sent by God to call away from, as we will see.

What Is Islām?

Islām is Submission to God and it is The Religion of Abraham, The Religion of all The Prophets and Messengers.

God said,

ومن يرغب عن ملة إبراهيم إلا من سفه نفسه ولقد اصطفيناه في الدنيا وإنه في الآخرة لمن الصالحين

“And who desires other than The Religion of Abraham except he who fools himself. And We certainly chose him in the world; and verily he, in the Hereafter, will indeed be from the righteous.”

إذ قال له ربه أسلم قال أسلمت لرب العالمين

“When said to him his Lord, ‘Submit’, he said, 'I have submitted to The Lord of The Worlds.’”

ووصى بها إبراهيم بنيه ويعقوب يا بني إن الله اصطفى لكم الدين فلا تموتن إلا وأنتم مسلمون

“And admonished with it Abraham his children and Jacob (Isra'eel), ‘O my sons, verily God has chosen for you The Religion, so do not die except while you are Muslims (Submittants to God).’”

The Qur'ān (The Reading), Surah Al-Baqarah

This is the religion that Abraham called his people to, as did Noah and Moses, and the religion which Jesus and Muhammad called their people to return to after they had strayed from The Religion of Abraham into Idol Worship and Predecessor Following.

And its most important part is the worship of God alone, The Creator and Sustainer of The Skies and The Earth, The One Who gives life and death, as we can see the concern of The Prophets at their passing away - as God said after the above,

أم كنتم شهداء إذ حضر يعقوب الموت إذ قال لبنيه ما تعبدون من بعدي قالوا نعبد إلهك وإله آبائك إبراهيم وإسماعيل وإسحاق إلها واحدا ونحن له مسلمون

"Or were you witnesses when death attended Jacob (Isra'eel) when he said to his sons, 'What will you worship after me?', they said, 'We worship your God and The God of your fathers, Abraham and Ishmael and Isaac; One God. And We are to Him Submittants (Muslims).'"

The Qur'ān (The Reading), Surah Al-Baqarah

And God sent His Books to call people to God's Religion, The Religion of Abraham, as He said,

يا أهل الكتاب لم تحاجون في إبراهيم وما أنزلت التوراة والإنجيل إلا من بعده أفلا تعقلون

“O People of The Book, why do you dispute amongst Abraham when The Torah and The Gospel were not sent down except after him. Do you not then reason?”

The Qur'ān (The Reading), Surat Āli 'Imrān

So The Muslims (Submittants To God) today believe in and follow The Qur'ān (The Reading), the same as the Muslims (Submittants To God) of The Nation of Jesus believed in and followed The Gospel and the Muslims (Submittants To God) of The Nation of Moses believed in and followed The Torah, The Books revealed in their time to their nations.

So from those who were called by their respective Messengers to return to God's Religion, there were some who submitted to God and believed and some who disbelieved.

As for the way of the Muslims and the disbelievers, God has informed us of them both when He said,

وإذا قيل لهم اتبعوا ما أنزل الله قالوا بل نتبع ما ألفينا عليه آباءنا

“And when it is said to them, ‘Follow what God sent down.’ They said, ‘Nay, we follow what we found upon it our fathers.’”

The Qur'ān (The Reading), Surah Al-Baqarah

So God has taught us that the way of the Muslims is following what God sent down - and the way of the disbelievers is following what they found their fathers upon.

What Is Belief?

Since Submission To God is The Religion of The Prophets and The Messengers, is it the case that every Muslim is a believer?

The answer is that no, there are Muslims who despite practicing Islām are not believers.

This is clear from reading God's Books, as it is clear in everyone's knowledge that it is possible to practice something openly while not believing in it.

God said,

ومن الناس من يقول آمنا بالله وباليوم الآخر وما هم بمؤمنين

“And from the people is who says, ‘We believe in God and in The Last Day,’ and they are not believers.”

The Qur'ān (The Reading), Surah Al-Baqarah

And God said,

قالت الأعراب آمنا قل لم تؤمنوا ولكن قولوا أسلمنا ولما يدخل الإيمان في قلوبكم وإن تطيعوا الله ورسوله لا يلتكم من أعمالكم شيئا إن الله غفور رحيم

“The Bedouins say, ‘We believe,’ say, ‘You have not believed, rather say, ‘We have submitted,’ and belief has not entered your hearts. And if you obey God and His Messenger, He will not deprive you from your deeds a thing. Indeed, God is Forgiving, Merciful.”

The Qur'ān (The Reading), Surah Al-Hujurāt

So Islām is Submission To God, and there are from The Muslims those in whose hearts belief has entered and those in which it hasn't yet.

Are There Believers From Other Religions?

So since Islām is God's Religion and The Religion of The Prophets and The Messengers, are there believers from the practicers of other religions?

The answer is yes, and there are Muslims from the practicers of other religions too. They are obligated, upon learning of Islām being God's Religion, to accept and believe in it, though if it has not reached them yet then they are not to be considered disbelievers.

God said,

إن الذين آمنوا والذين هادوا والنصارى والصابئين من آمن بالله واليوم الآخر وعمل صالحا فلهم أجرهم عند ربهم ولا خوف عليهم ولا هم يحزنون

“Indeed those who believed and those who practiced Judaism and The Christians and The Sabeans who believed in God and The Last Day and did righteous deeds, then for them is their reward with their Lord and no fear is upon them and they not grieve.”

The Qur'ān (The Reading), Surah Al-Baqarah

And He said,

الذين آتيناهم الكتاب من قبله هم به يؤمنون

“Those who We gave them The Book from before it, they are believers in it.”

وإذا يتلى عليهم قالوا آمنا به إنه الحق من ربنا إنا كنا من قبله مسلمين

“And when recited upon them they said, ‘We have believed in it, indeed it is The Truth from our Lord. Indeed, we were from before it Muslims (Submittants).’”

The Qur'ān (The Reading), Surah Al-Qasas

So there are from The People of The Book those who are Submittants and those who are believers. When God's Verses are recited upon them they believe and accept them and return to The Religion of their father Abraham, as they did in the lifetime of Jesus and Muhammad.

Enter Tribulation

So in the 1400 years since the sending of The Prophet Muhammad to call, not just his people, but every single person back to God's Religion before the coming of The Hour, there have been a large number of people who accepted, the praise belongs to God.

Every so often, there are tribulations that test this nation, as the nations before us were tested.

God said,

أحسب الناس أن يتركوا أن يقولوا آمنا وهم لا يفتنون

“Do the people reckon that they be left that they said, ‘We believe,' and they will not be tested?”

The Qur'ān (The Reading), Surah Al-Ankaboot

And the reason for these trials is due to straying from following what God sent down as we should, and the way out of these trials is by simply returning to what God sent down - as God said,

ظهر الفساد في البر والبحر بما كسبت أيدي الناس ليذيقهم بعض الذي عملوا لعلهم يرجعون

“Corruption has appeared amongst land and sea at what the hands of men have earned, that He make them taste part of what they have done, that they might return.”

The Qur'ān (The Reading), Surah Al-Rūm

Sadly, instead of simply returning to following what God sent down as we've been commanded, there are groups that appear (due to ignorance, mistakes or seeking worldly gain) in different times and places who have done practices contrary to God's Religion.

Some of these groups include The Shi'ah who practice Sectarianism, Revolutions and Predecessor Worship (all of which are obviously prohibited in God's Religion) and different political groups who seek after political power - which is likewise prohibited for Muslims - but all of them practice something other than simply following what God sent down as we've been commanded.

There are the Madhhabs, groups built around the following of certain knowledgeable Muslims from the past instead of what God sent down, the Sufis who practice esoteric emotional stuff that is nothing to do with Islām and other groups beside.

What they are all have in common however, is practicing something other than simply following what God sent down.

One of the more recent groups that have appeared are the ones who call themselves Salafis.

They have left following what God sent down and instead follow predecessors from the Muslims.

So in essence, there is no difference between them and the Madhhabs and any other sect that follow predecessors instead of what God sent down.

This is prohibited, of course, as God said,

اتبعوا ما أنزل إليكم من ربكم ولا تتبعوا من دونه أولياء قليلا ما تذكرون

“Follow what has been sent down to you from your Lord and do not follow from besides Him allies. Little do you remember.”

The Qur'ān (The Reading), Surah Al-A'rāf

And God said,

وإذا قيل لهم اتبعوا ما أنزل الله قالوا بل نتبع ما ألفينا عليه آباءنا

“And when it is said to them, ‘Follow what God sent down.’ They said, ‘Nay, we follow what we found our fathers upon.’”

The Qur'ān (The Reading), Surat Al-Baqarah

And in fact, there is no difference in their way and the way of the disbelievers who likewise follow their predecessors - except that they hopefully do believe in God's Books and His Messengers, yet their way of acting is the same as the disbelievers as we've seen.

So as with every other group, they are obligated to leave following other than what God sent down and return to following it alone.

God said,

وجاهدوا في الله حق جهاده هو اجتباكم وما جعل عليكم في الدين من حرج ملة أبيكم إبراهيم هو سماكم المسلمين من قبل وفي هذا ليكون الرسول شهيدا عليكم وتكونوا شهداء على الناس فأقيموا الصلاة وآتوا الزكاة واعتصموا بالله هو مولاكم فنعم المولى ونعم النصير

“And strive in God, the striving due to Him, He has chosen you and not made upon you in The Religion from hardship. The Religion of your father Abraham. He called you Muslims from before and in this, that The Messenger be a witness over you and you be witnesses over the people. So establish The Prayer and give The Obligatory Charity and hold fast to God, He is your Patron. So blessed is The Patron and blessed is The Helper.”

The Qur'ān (The Reading), Surah Al-Hajj

بسْمِ اللَّهِ الرَّحْمَٰنِ الرَّحِيمِ

In The Name of God, The Vastly Merciful, The Merciful

الْحَمْدُ لِلَّهِ رَبِّ الْعَالَمِينَ

The praise belongs to God, The Lord of The Worlds.

الرَّحْمَٰنِ الرَّحِيمِ

The Vastly Merciful, The Merciful

مَلِكِ يَوْمِ الدِّينِ

King of The Day of Reckoning.

إِيَّاكَ نَعْبُدُ وَإِيَّاكَ نَسْتَعِينُ

You we worship and You we seek aid.

اهْدِنَا الصِّرَاطَ الْمُسْتَقِيمَ

Guide us to The Straight Path.

صِرَاطَ الَّذِينَ أَنْعَمْتَ عَلَيْهِمْ غَيْرِ الْمَغْضُوبِ عَلَيْهِمْ وَلَا الضَّالِّينَ

The Path of whom You have favoured upon them, other than those whom anger is upon them and the astray.

The Qur’ān (The Reading), Al-Fātiḥah (The Opening)