Do not love the world or the things in the world. If anyone loves the world, the love of the Father is not in him, 1 John 2:15 (NKJV).
We are called to be set apart for God and to not conform to the things of this world, however, it seems more and more that people who profess to be Christians look so much like the world it's hard to tell them apart.
Being a Christian is so much more than just saying, "I believe in Jesus." Being a Christian means following Jesus, and obeying the word of God. If our lives are going to change the lives of those who do not know the Lord, then our lives cannot be like the ones who do not know the Lord. We are called to be set apart, to be holy, to be pure in our speech, our dress, and our actions. We are called to be like Jesus, not like the world.
There is a way that seems right to man, but it's end is death (Proverbs 14:12).
Conforming to this world is doing the things of the world. Going to R-rated movies, drinking alcohol at the club with friends, dressing the way that people in this world dress, using vulgar speech, telling off-color jokes, participating in activities that everyone else does, having sex outside of marriage, living with someone you're not married to, and the list goes on. I know people who profess to be Christians who think nothing of going to the casino and gambling. I know people who profess to be Christians who still smoke and drink. On social media I see pictures with lots of cleavage, and more, that are posted by people who profess to be Christians. I see people who profess to be Christians conforming to the ways of this world by participating in the things of this world, by going along with things that the Bible strictly opposes, because when you don't take a stand against the world then you are standing for the world.
The Bible says, "Be holy for I am Holy" (1 Peter 1:16). That may seem impossible but it's not. We are not to conform to this world, we are to conform to what the Bible tells us is right and pure and holy. We might not achieve Holiness in this life but we are to strive for it. We are to put away the things of this world and to walk the walk and talk the talk the way that Jesus did.
Sitting in a church on Sunday does not make you a Christian any more than sitting in your garage makes you a car. Following Jesus and obeying the word of God is what makes you a Christian.
I hear people complaining all of the time that they go to church on Sunday yet their life is not blessed. Blessings do not come from sitting in a church. Blessings come from living out a Christian life every single day of the week. A Sunday Christian will not have a blessed life.