Monotheism and Dutifulness to parents

1⃣- Allah, the Great Creator, commanded us not to polytheism, and to worship Him alone and not associate anything with Him. 

And He Almighty made it clear to us that polytheism is a great injustice.

In the holy Qur'an Allah says: 

(وَإِذۡ قَالَ لُقۡمَٰنُ لِٱبۡنِهِۦ وَهُوَ يَعِظُهُۥ يَٰبُنَيَّ لَا تُشۡرِكۡ بِٱللَّهِۖ إِنَّ ٱلشِّرۡكَ لَظُلۡمٌ عَظِيمٞ )

سورة لقمان :١٣ 

(13) And [mention, O Muḥammad], when Luqmān said to his son while he was instructing him, "O my son, do not associate [anything] with Allāh. Indeed, association [with Him] is great injustice." 

﴾Qur'an - Surat Luqmān 31:13﴿

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2⃣ And Allah Subhanahu wa Ta'la has enjoined upon us to care for our parents and to be thankful to them, because of the greatness of the position of the parents.

In the holy Qur'an Allah says:

وَوَصَّيۡنَا ٱلۡإِنسَٰنَ بِوَٰلِدَيۡهِ حَمَلَتۡهُ أُمُّهُۥ وَهۡنًا عَلَىٰ وَهۡنٖ وَفِصَٰلُهُۥ فِي عَامَيۡنِ أَنِ ٱشۡكُرۡ لِي وَلِوَٰلِدَيۡكَ إِلَيَّ ٱلۡمَصِير

سورة لقمان :(١٤)

(14) And We have enjoined upon man [care] for his parents. His mother carried him, [increasing her] in weakness upon weakness, and his weaning is in two years. Be grateful to Me and to your parents; to Me is the [final] destination. 

﴾Qur'an - Surat Luqmān 31:14﴿

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3-And Allah The most Merciful, guided us to be kind to our parents, to obey them in good, and to disobey them in polytheism.

In the holy Qur'an Allah says:

وَإِن جَٰهَدَاكَ عَلَىٰٓ أَن تُشۡرِكَ بِي مَا لَيۡسَ لَكَ بِهِۦ عِلۡمٞ فَلَا تُطِعۡهُمَاۖ وَصَاحِبۡهُمَا فِي ٱلدُّنۡيَا مَعۡرُوفٗاۖ وَٱتَّبِعۡ سَبِيلَ مَنۡ أَنَابَ إِلَيَّۚ ثُمَّ إِلَيَّ مَرۡجِعُكُمۡ فَأُنَبِّئُكُم بِمَا كُنتُمۡ تَعۡمَلُونَ

سورة لقمان :(١٥) )

(15) But if they endeavor to make you associate with Me that of which you have no knowledge,[1161] do not obey them but accompany them in [this] world with appropriate kindness and follow the way of those who turn back to Me [in repentance]. Then to Me will be your return, and I will inform you about what you used to do.

﴾Qur'an - Surat Luqmān 31:15﴿

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💎So we must obey our parents, and be kind to them, except for polytheism

_And insha'Allah this kindness and gentleness towards them will soften their hearts and encourage them to join Islam