I'm a Christian and the question of haram just doesn't apply. There are no haram/non kosher foods in Christianity. To claim that God dislikes us for eating certain things or to claim that we somehow break some divine law by eating non-haram foods is wrong as our religion doesn't say so. So, of course, giving a Christian friend non-haram food is perfectly ok.
According to this fatwa on islamweb #48460 (in Arabic).
Your interpretation of the significant parts is simply wrong:
O Allah! We implore You for help and beg forgiveness of You and believe in You and rely on You and extol You and we are thankful to You and are not ungrateful to You and we alienate and forsake those who disobey You.
اللهم إنا نستعينك ...
It is allowed to accept gifts from non-Muslims on their festivals.
As for the food, it is allowed to accept and eat the food that has no meat in it and nothing else haram.
'ʻAli may Allaah be pleased with him was given a gift on the Nayrooz festival (Persian festival) and asked, 'What is this?' They replied, 'Oh, Leader of the Believers, today is Nayrooz ...
The Ahl al-Dhimma are permitted to worship according to their religion, because peace has been made with them on the condition of paying Jizyah and not on the condition of abandoning their religion.
قاتلوا ... حتى يعطوا الجزية
Fight ... until they give the jizyah
— Quran 9:29
فإن هم أبوا فسلهم الجزية فإن هم أجابوك فاقبل منهم وكف عنهم