Christianity is never situational. In the Bible, Jesus did not say to let your light shine to those who are nice to you. He did not say to be kind and generous only to those who are fellow Christians. We are supposed to show Jesus to everyone, everywhere, all the time.
While we know that fact deep down inside, we do not always live that fact. We often only want to do good things for those who have done good things for us. Or we only want to do good things for those who we think will do good things for us, or for others. We are tempted to think along the lines of, “I will help someone, but not if I think they aren’t all that good.” Sometimes, we will even say something like that out loud, which I am sure would make Jesus shake his head in disbelief.
No, we are not commanded to act like Christians only toward other Christians. We are not even commanded to act like Christians only toward those who we think have a really good chance of becoming Christians. Instead, Jesus expects us to act like Christians toward everyone, no matter what their situation, their motive, or their background.
Christianity is not situational. Let your light shine in all situations!