The incident of ‘Umar ibn Al-Khattab رضي الله عنه accepting Islam is well known. There are a few points that I'd like to highlight in this brief post.
1. You probably remember that whilst ‘Umar was on his way to seek out the Prophet ﷺ intending to kill him, he encountered one of his tribesmen, Nu‘aym ibn Abdillāh رضي الله عنه, who directed him to his sister’s house, telling him that she had accepted Islam along with her husband, Sa‘id ibn Zayd, and that he ought to put his own house in order first.
The issue that can be raised here is that the Ṣaḥābī Nu‘aym رضي الله عنه effectively ‘sold out’ ‘Umar’s sister and brother in-law, throwing them in harm’s way. ‘Umar had not known of their conversion up until that point, and divulging that secret to him meant that in his rage, he would definitely deal with them.
Put into context however, this was a shrewd move on the part of Nu‘aym. He took a calculated risk and in the spur of the moment, made the right call. By sending ‘Umar in the direction of his sister, he could now forewarn the Prophet ﷺ of ‘Umar’s intentions, and the Prophet ﷺ would be prepared for him. Secondly, being his sister and a female, the chances ‘Umar would harm her significantly were very less. This was because of the bond of kinship, and mutual respect for a female. The intelligence of Nu‘aym ibn Abdillah رضي الله عنه is often overlooked in the significance of the whole incident, yet it is more than worthy of being commended.
2. It is reported that after the episode with his sister, when ‘Umar eventually came into the presence of the Prophet ﷺ, the Prophet ﷺ grabbed him by the front of his shirt and shook him roughly, before asking him why he had come.
The bravery and strength of ‘Umar is what most people remember him for, yet this incident proves that even Umar’s bravery and strength were no match for the fearlessness of the Messenger, his strength and bravery ﷺ.
3. Ibn Mas‘ūd رضي الله عنه states, “By Allah! We weren’t able to perform Ṣalāh near the Ka‘bah until ‘Umar accepted Islam.” By this, he means that those Companions who had less of a social support network in Makkah at the time could not perform Ṣalāh near the Ka‘bah in fear of being persecuted. This changed when ‘Umar accepted Islam, because his influence and strength gave them that support. We learn from this that there is no harm whatsoever in wishing and praying for the Islam of influential people in society, as that is a means of da‘wah and a door which leads to many others embracing the faith. The Prophet ﷺ actually asked Allah to guide ‘Umar for this very purpose.
Based on that, someone who is blessed with influence in society can do so much for Islam through their influence; even more so than those who have spent their lives in learning, propagating and striving for it. Therefore, never underestimate even the little Muslim celebrities might do in regards their faith; it could be much more valuable a PR exercise than everything you do in your entire life.
...ذَلِكَ فَضۡلُ ٱللَّهِ يُؤۡتِيهِ مَن يَشَآءُ ۚ وَٱللَّهُ وٰسِعٌ عَلِيمٌ
‘...that is the Grace of Allah, which He bestows upon whomsoever He wishes.’ (5:54)
 أخرج قصة إسلام عمر -رضي الله عنه-: الإمام أحمد في فضائل الصحابة - رقم الحديث (٣٧٦) - والحاكم في المستدرك - كتاب معرفة الصحابة - باب استقامة فاطمة على الإسلام - رقم الحديث (٦٩٨١) - وابن سعد في طبقاته (٣/١٤٢) - وسندها ضعيف - وأخرجها ابن إسحاق في السيرة (١/٣٨١) بدون سند.
قال الإمام البخاري فيما نقله عنه الحافظ في لسان الميزان (٥/٥٠٢) في ترجمة: قاسم بن عثمان البصري - أحد رواة قصة إسلام عمر -رضي الله عنه-: له أحاديث لا يتابع عليها.
وقال الحافظ في لسان الميزان (٥/٥٠٣): في ترجمة قاسم بن عثمان البصري حدث عنه إسحاق الأزرق بمتن محفوظ، وبقصة إسلام عمر -رضي الله عنه-، وهي منكرة جدا.
 فقال رسول الله -صلى الله عليه وسلم-: "ائذن له"، ففتحوا له، ونهض إليه رسول الله -صلى الله عليه وسلم- حتى لقيه، فأخذ بمجامع ثوبه، ثم جذبه جذبة شديدة، فما تمالك عمر أن وقع على ركبتيه على الأرض، فقال له -صلى الله عليه وسلم-: "ما جاء بك يا ابن الخطاب؟ ، فوالله ما أرى أن تنتهي حتى ينزل الله بك قارعة"
 قال الحافظ في الإصابة: وروى الإمام أحمد في فضائل الصحابة، والحاكم في المستدرك بسند حسن عن ابن مسعود -رضي الله عنه- قال: كان إسلام عمر فتحا، وهجرته نصرا، وإمارته رحمة، والله ما استطعنا أن نصلي حول البيت ظاهرين حتى أسلم عمر