ما هي خطيئة آدم التي يزعم المسيحيون أن المسيح صلب لفدائها، وهل صُلب المسيح حقًا، وهل يسوع هو النبي عيسى عليه السلام، وكيف يعتبرونه إلهًا، وما مدى صحة هذه المزاعم؟

The false beliefs among Christians mentioned in the question are: The Inherited Sin of Adam: Humans are not held accountable for the sin of another, as Allah Almighty said: {That no bearer of burdens will bear the burden of another}. The Crucifixion of Christ: The crucifixion of Christ did not occur; rather, he was raised to Allah, as stated in the Holy Qur'an: {And they did not kill him, nor did they crucify him; but [rather], it was made to appear to them}. The Deification of Christ: This is from their extremism and misguidance, which Allah has condemned them for.

It is not permissible for a Muslim to take a disbeliever as a friend, based on the hadith: "Do not associate except with a believer." However, if circumstances necessitate interacting with them, one should treat them kindly, deal justly with them, and invite them to Islam.