Making sister to a non muslim
Assalamualaikum…i am 18 yrs old and currently i am studying i am not talking to any of the non mehram unnecessarily but whenever i talks i tell them sister …i am going to computer classes and in that coaching classes one small sister is teaching to me i have made her sister and she also tells me brother if she wants to shake hands with me is it a sin for me my affection and love for her is like a own sister .
Answer
WaʿAlaykum Salām Wa Raḥmatullāhī Wa Barakātuh
It should be noted that the rulings laid out by the Sharīʿah are general and applies to all with certain exceptions based on legitimate reasoning and specific scenarios.
In principle, it is unlawful to shake hands with a non-Maḥram person of the opposite gender, and having affection and love for her like that of a real sister will not be legitimate grounds to render her a Maḥram and to validate such a practice.