First of all, it means believing that Christ is your savior - that He died and rose again for you.
Second, it means taking opportunities in life, as they present themselves, to behave as He would desire us too.
Since we are all sinners saved by grace, our day to day lives can appear to some who like to judge, to be too worldly - but that is for no one else to judge but us alone. What you watch and listen to doesn't define your Christian walk. There are different administrations of the Holy Spirit and the Lord can be found in all things, often in the things judged by the wise to be the least. (see 1 Cor. 1:27-28)
The Pharisees tried to point condemning fingers at Yahshua because of the places he went and the people he hung out with. He ate meals with publicans and sinners, and he drank wine.
Being a Christian is being a merciful, compassionate person who believes in Christ, not a superfluous appearance of goodness and piety.
Take grace and do righteously.