What does a Christian look like? Certainly, a Christian can look like anyone, right? Because anyone can be a Christian. But let me put forth another idea. You can better tell a Christian by their actions than their appearance. I would say people judge you more based on what you do than how you look. So that ”how can you tell if a person is a Christian?” is based on how they act, not how to dress.
Note the verse above. Three things that come from God are being chosen, holiness, and being dearly loved. Because of those three things, things which we have no power to do ourselves, we acquire and practice the following character traits. These traits help define our character, and we do not achieve them all at once. It takes time and practice to go develop compassion. It takes effort to develop kindness and gentleness. We have to work to suppress pride to humility. Patience, well, you learn through experience. All of these things are within our power to do. But we also have the power of the Holy Spirit to help us be more Christlike. A good person might have one or more of these qualities, but all of them? No. A Christian needs the peaceful contented presence of the Holy Spirit to be able to hold all of these at the same time, to practice to a greater or lesser degree each in turn.
How can you tell a Christian? It’s not by the words they say or how they dress. Watch what they do. Watch what you do. Are you a Christian?