السلام عليكم ورحمة الله وبركاته أحسن الله إليكم as a continue of the question about the kaafir trying to be my friend , would it be fine for me to say "You left the religion of Allah and the truth We cannot be friends , and if you come back (meaning to islam) then we can gladly be friends"

Ustadh AbdulAziz al-Haqqan

It sounds more like an argument to me. It is your choice, but becareful from affecting your religion.