فَلَا تُطِعِ الْكَافِرِينَ وَجَاهِدْهُمْ بِهِ جِهَادًا كَبِيرًا ﴿۵۲﴾ وَهُوَ الَّذِي مَرَجَ الْبَحْرَيْنِ هَذَا عَذْبٌ فُرَاتٌ وَهَذَا مِلْحٌ أُجَاجٌ وَجَعَلَ بَيْنَهُمَا بَرْزَخًا وَحِجْرًا مَحْجُورًا ﴿۵۳﴾ وَهُوَ الَّذِي خَلَقَ مِنَ الْمَاءِ بَشَرًا فَجَعَلَهُ نَسَبًا وَصِهْرًا وَكَانَ رَبُّكَ قَدِيرًا ﴿۵۴﴾ وَيَعْبُدُونَ مِنْ دُونِ اللَّهِ مَا لَا يَنْفَعُهُمْ وَلَا يَضُرُّهُمْ وَكَانَ الْكَافِرُ عَلَى رَبِّهِ ظَهِيرًا ﴿۵۵﴾ وَمَا أَرْسَلْنَاكَ إِلَّا مُبَشِّرًا وَنَذِيرًا ﴿۵۶﴾

﴾52﴿ Falaa tuti'il kaafireena wa jaahidhum bihee jihaadan kabeeraa
﴾53﴿ Wa Huwal lazee marajal bahraini haazaa 'azbun furaatunw wa haazaa milhun ujaaj; wa ja'ala bainahumaa barzakhanw wa hijran mahjooraa
﴾54﴿ Wa Huwal lazee khalaqa minal maaa'i basharan fa ja'alahoo nasaban wa sihraa; wa kaana Rabbuka Qadeeraa
﴾55﴿ Wa ya'budoona min doonil laahi maa laa yanfa'uhum wa laa yadurruhum; wa kaanal kaafiru 'alaa Rabbihee zaheeraa
﴾56﴿ Wa maa arsalnaaka illaa mubashshiranw wa nazeeraa

﴾52﴿ So do not obey the disbelievers, and strive against them with this Qur'an, a great striving
﴾53﴿ And Allah, the Exalted, is the One who has made the two seas flow side by side: one fresh and sweet, quenching thirst, and the other salty and bitter, harsh to swallow. And We placed between them a barrier and a firm, impenetrable partition
﴾54﴿ And it is Allah, the Exalted, who created the human being from water (a drop of fluid), then made him one of lineage and in-laws. And your Lord is All-Powerful
﴾55﴿ And they worship besides Allah someone who can neither benefit them nor harm them, and the disbeliever turns his back on his Lord
﴾56﴿ And We have not sent you except as a bearer of good news and a warner

[52] In this verse, encouragement is given and the method of invitation is shown to the Prophet (May Allah bless him and give him peace).
That is, these disbelievers invite you to polytheism or to conceal the truth, so do not accept their words.
And "strive with the Qur'an" means to exert great effort in preaching the Qur'an and to use all your strength so that there is no weakness in it.
This is referred to as the great struggle (Jihad Kabir).
[53] This is another rational proof, and in it two types of water are mentioned: the sweet water of rivers and rain in the plains, and the salty water of the seas.
Though they flow into the sea, they do not mix with each other.
“Maraja” means they are left to flow freely, but without mixing.
“Barzakh” is a barrier that prevents one from overpowering the other, such that the sweet becomes salty.
“Hijran Mahjura” is a prevention from mixing and uniting.
However, this barrier is not tangible.
Something similar is mentioned in Surah Ar-Rahman (verse 20).
[54] This is another rational proof, and after the act of creation, two blessings are mentioned: through creation, lineage is established, and through marriage, affinity (in-law relationships) is formed.
Both of these serve as means for the protection of human beings and the continuation of humanity.
[55] Among the evidences, it gives a warning against associating partners in worship.
“ʿAlā Rabbihi ẓahīrā” means that in opposition to the oneness of Allah the Exalted and in opposition to the party of Allah, they side with Satan and strive to make polytheism dominant and spread it.
Or, “ẓahīr” can mean someone lowly and humiliated.
[56] In this verse, there is consolation and affirmation of the truthfulness of the Messenger.
The point is that in response to polytheism in worship, a Messenger has been sent.