Yes, Christians should act like Christians....sort of. To me, this means to love and seek after God continually/continuously and to love your neighbour. Those who are newly saved and just learning to seek God might have many behaviours that are contrary to the Christian life. But if they are continually growing and letting the Spirit guide them, then they are doing what's right. After I came back to God, I stopped sinning intentionally, but I did (and still do!) many things wrong. I can honestly say though, that when the Spirit points out to me something I need to change, I set about struggling to do so, with the Spirit's help. There is fruit in my life though, little fruit at first that keeps growing as I keep following God. "You will know them by their fruit". Fruit can take time to grow. If all someone's faith is is a set of 'beliefs' and nothing else, I'd try to help that person find a deeper Christian life. I believe people can be saved simply from a faith in Jesus even if they never do anything else, but what kind of life is that?