Humans need to worship and serve God, it is the purpose of their creation.
وَمَا خَلَقْتُ الْجِنَّ وَالْإِنسَ إِلَّا لِيَعْبُدُونِ
And I created not the Jinn and Mankind except that they should worship Me (Alone). (Quran 51:56)
Allah is the same God who revealed Himself to the Biblical Prophets.
قَالَتْ رُسُلُهُمْ أَفِي اللّهِ شَكٌّ فَاطِرِ السَّمَاوَاتِ وَالأَرْضِ
Their Messengers said: "What! Can there be a doubt about Allah, the Creator of the Heavens and the Earth?" (Quran 14:10)
Allah is our Creator Who originated and maintains everything.
أَمْ خُلِقُوا مِنْ غَيْرِ شَيْءٍ أَمْ هُمُ الْخَالِقُونَ أَمْ خَلَقُوا السَّمَاوَاتِ وَالْأَرْضَ بَل لَّا يُوقِنُونَ
Were they created by nothing? Or were they themselves the creators? Or did they create the Heavens and the Earth? No, but they have no firm belief. (Quran 52:35-6)
Precise proof of Allah is found in the Quran, we cannot see Him in this world.
وَمَا أُوتِيتُم مِّن الْعِلْمِ إِلاَّ قَلِيلاً
And of knowledge, you (humans) have been given only a little. (Quran 17:85)
The diverse universe has been created by Allah’s intelligent design.
وَكَأَيِّن مِّن آيَةٍ فِي السَّمَاوَاتِ وَالأَرْضِ يَمُرُّونَ عَلَيْهَا وَهُمْ عَنْهَا مُعْرِضُونَ
How many a sign is there in the heavens and the earth, which they pass by with their faces turned away! (Quran 12:105)
Allah’s Laws govern the universe and all of creation praises Him.
تُسَبِّحُ لَهُ السَّمَاوَاتُ السَّبْعُ وَالأَرْضُ وَمَن فِيهِنَّ وَإِن مِّن شَيْءٍ إِلاَّ يُسَبِّحُ بِحَمْدَهِ وَلَـكِن لاَّ تَفْقَهُونَ تَسْبِيحَهُمْ
The seven heavens and the Earth and all that is therein glorify Him, and there is not a thing but celebrates His praise, but you do not understand their praise. (Quran 17:44)
Humans are born with an in-built, yet corruptible knowledge of Allah.
"Every child is born with an innate disposition (fitrah), but his parents turn him into a Jew or Christian (and other than that). It is like when an animal gives birth to normal offspring; have you noticed any (young animal) born branded (mutilated with the mark of its owners) before they are branded?" (Hadith)
Humans instinctively turn to Allah in times of need.
وَإِذَا مَسَّ الْإِنسَانَ ضُرٌّ دَعَا رَبَّهُ مُنِيبًا إِلَيْهِ ثُمَّ إِذَا خَوَّلَهُ نِعْمَةً مِّنْهُ نَسِيَ مَا كَانَ يَدْعُو إِلَيْهِ مِن قَبْلُ وَجَعَلَ لِلَّهِ أَندَادًا
And when a calamity touches man, he calls to his Lord, turning repentant to Him. Then, when He grants him a favor from Himself, he forgets that for which he called to Him before, and sets up partners as rivals to Allah. (Quran 39:8)
Allah, our Maker, knows best how we can function properly.
إِنَّا خَلَقْنَا الْإِنسَانَ مِن نُّطْفَةٍ أَمْشَاجٍ نَّبْتَلِيهِ فَجَعَلْنَاهُ سَمِيعًا بَصِيرًا إِنَّا هَدَيْنَاهُ السَّبِيلَ إِمَّا شَاكِرًا وَإِمَّا كَفُورًا
Verily, We have created man out of drops of mixed sexual discharge, in order to try him: so We made him to hear and to see. Verily, We showed him the way, whether he be grateful or ungrateful. (Quran 76:2-3)
أَلَا يَعْلَمُ مَنْ خَلَقَ
Should He not know what He created? (Quran 67:14).
Allah guides to Islam who He likes as a blessing.
يَهْدِي بِهِ اللّهُ مَنِ اتَّبَعَ رِضْوَانَهُ سُبُلَ السَّلاَمِ وَيُخْرِجُهُم مِّنِ الظُّلُمَاتِ إِلَى النُّورِ بِإِذْنِهِ وَيَهْدِيهِمْ إِلَى صِرَاطٍ مُّسْتَقِيمٍ
Wherewith Allah guides all those who seek His Good Pleasure to ways of peace. And He brings them out of darkness by His Will into light and guides them to the straight way. (Quran 5:16)