2 Peter 2:20
For if, after they have escaped the pollutions of the world through the knowledge of the Lord and Savior Jesus Christ, they are again entangled in them and overcome, the latter end is worse for them than the beginning.
2 Peter 2:21
For it would have been better for them not to have known the way of righteousness, than having known [it], to turn from the holy commandment delivered to them.
2 Peter 2:22
But it has happened to them according to the true proverb: "A dog returns to his own vomit," [fn] and, "a sow, having washed, to her wallowing in the mire."

Ooh!!!! these are very harsh words from Peter to all of us, but very true...We Christian believed that as soon as we say the "Prayer of salvation" we are in God's side and we can go on living the same way before we came to Christ.
We don't understand that coming to Jesus was only the beginning...after coming to Jesus we need to get to know Him...How do we do that? By reading His word every day (Bible) and changing your heart, humbling your self and putting away the old you.
"For it would have been better for them not to have known the way of righteousness" If we know the truth about Jesus and we ignore His Commandments is like saying "I know you but I don't care about you", "thanks but no thanks" I don't want to know what God will do about people like that. The day of judgment is at hand and we don't want to be left behind and cast to the lake of fire. You want to believed it or not, hell is as real as Heaven.