Titus 1:16 — They claim to know God, but by their actions they deny him. They are detestable, disobedient and unfit for doing anything good.
That is a strong thing to say, but it speaks very clearly. People who claim to know God, but don’t really are bad people. This is called practical atheism. Practical atheists are people who are Christian in name, but act as if they don’t know God. They may act kind, and be nice in public, but deep down they only do it for themselves and other humans.
So, what does a Christian life look like? A Christian life is one that is changed because God is there. Not just changed superficially, but really changed. Think of it this way: If God were suddenly to stop existing a practical atheist life wouldn’t change, but a Christian life would be drastically changed.
A Christian life should be changed by God, but what does that look like? It looks like a true love for others (not just a give and take love), and a true love for God. It can also look like miracles, and revelations from God. True sacrifice and fully giving oneself to God are also signs of a Christian life. If none of these are present then how is God present. If church is just a social club how is it different than basketball?
Let me finish by asking a question:
If God didn’t exist would your life change?