إِنَّمَا ذَلِكُمُ الشَّيْطَانُ يُخَوِّفُ أَوْلِيَاءهُ
It is only Shaytan that suggests to you the fear of his friends,
meaning, Shaytan threatens you with his friends and tries to pretend they are powerful and fearsome.
Allah said next,
فَلَ تَخَافُوهُمْ وَخَافُونِ إِن كُنتُم مُّوْمِنِينَ
so fear them not, but fear Me, if you are indeed believers.
meaning, "If Shaytan brings these thoughts to you, then depend on Me and seek refuge with Me. Indeed, I shall suffice you and make you prevail over them."
Similarly, Allah said,
أَلَيْسَ اللَّهُ بِكَافٍ عَبْدَهُ
وَيُخَوِّفُونَكَ بِالَّذِينَ مِن دُونِهِ
Is not Allah Sufficient for His servant! Yet they try to frighten you with those besides Him! (39;36) until,
قُلْ حَسْبِيَ اللَّهُ
عَلَيْهِ يَتَوَكَّلُ الْمُتَوَكِّلُونَ
Say;"Sufficient for me is Allah; in Him those who trust must put their trust." (39;38)
Allah said,
فَقَـتِلُواْ أَوْلِيَاءَ الشَّيْطَـنِ إِنَّ كَيْدَ الشَّيْطَـنِ كَانَ ضَعِيفاً
So fight you against the friends of Shaytan; ever feeble indeed is the plot of Shaytan. (4;76)
and,
أُوْلَـيِكَ حِزْبُ الشَّيْطَـنِ أَلَا إِنَّ حِزْبَ الشَّيْطَـنِ هُمُ الخَـسِرُونَ
They are the party of Shaytan. Verily, it is the party of Shaytan that will be the losers! (58;19)
كَتَبَ اللَّهُ لاّغْلِبَنَّ أَنَاْ وَرُسُلِى إِنَّ اللَّهَ قَوِىٌّ عَزِيزٌ
Allah has decreed;"Verily, it is I and My Messengers who shall be the victorious." Verily, Allah is All-Powerful, All-Mighty. (58;21)
and,
وَلَيَنصُرَنَّ اللَّهُ مَن يَنصُرُهُ
Verily, Allah will help those who help His (cause). (22;40)
and,
يأَيُّهَا الَّذِينَ ءَامَنُواْ إِن تَنصُرُواْ اللَّهَ يَنصُرْكُمْ
O you who believe! If you help (in the cause of) Allah, He will help you. (47;7)
and,
إِنَّا لَنَنصُرُ رُسُلَنَا وَالَّذِينَ ءَامَنُواْ فِى الْحَيَوةِ الدُّنْيَا وَيَوْمَ يَقُومُ الاٌّشْهَـدُ
يَوْمَ لَا يَنفَعُ الظَّـلِمِينَ مَعْذِرَتُهُمْ وَلَهُمُ الْلَّعْنَةُ وَلَهُمْ سُوءُ الدَّارِ
Verily, We will indeed make victorious Our Messengers and those who believe, in this world's life and on the Day when the witnesses will stand forth. The Day when their excuses will be of no profit to wrongdoers. Theirs will be the curse, and theirs will be the evil abode. (40;51,52