The Conclusion of the Believer's Words, and the ultimate Destiny of both Parties
That believer said: `Why do I call you to salvation, which is the worship of Allah alone with no partner or associate, and belief in His Messenger, whom He has sent,'
(while you call me to the Fire! You invite me to disbelieve in Allah, and to join partners in worship with Him of which I have no knowledge;) means, on the basis of ignorance, with no proof or evidence.
وَأَنَاْ أَدْعُوكُمْ إِلَى الْعَزِيزِ الْغَفَّارِ
(and I invite you to the Almighty, the Oft-Forgiving!) means, with all His might and pride, He still forgives the sin of the one who repents to Him.
This has been mentioned in verse 45 in the following words: فَوَقَاهُ اللَّـهُ سَيِّئَاتِ مَا مَكَرُوا وَحَاقَ بِآلِ فِرْعَوْنَ سُوءُ الْعَذَابِ (Then Allah saved him from the evils of what they designed, and the House of the Pharaoh was encircled by an evil punishment.), that is, Allah Ta’ ala saved the believer from the harm the people of Pharaoh planned to bring to him, but they themselves were seized by a severe punishment. First of all, Allah Ta’ ala, in His mercy, saved the believer belonging to the House of Pharaoh right here in this world from the aggressive designs of the people of the Pharaoh against him, the details of which have not been mentioned in the Qur'an. But, the words of the Qur'an seem to say simply that the people of the Pharaoh had made many plans to hurt and kill him, and when the people of Pharaoh were drowned, Allah Ta ala saved this believing servant of Allah along with Sayyidna Musa (علیہ السلام) . As for salvation in the Hereafter, it is fairly obvious.
Tazkirul Quran
Maulana Wahiduddin KhanOn ayahs 41–45
In other words the sentence, ‘I call you towards the Lord of the Universe, whereas you call me towards one who is quite ineffectual both in this world and in the Hereafter.’ This presents the gist of the speech of a true believer. This gives an idea of what was being discussed in Pharaoh’s court. The discussion was on whether God or other man-made deities should be invoked. The true believer said that God is a living and dominant entity. Calling upon Him amounts to calling upon the real God. As opposed to this, he said that their deities were only the creation of their imagination or objects of superstition, and were of no avail either in this world or in the world Hereafter. When they (the deities) have no real existence, how can they confer any real advantage? (Tafsir ibn Kathir, vol. IV, p. 80).
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.