Lets being plane with ourselves, sometimes as a born again Christian we found ourselves thinking stuffs we clearly know it's not of God. And our defence will be like, "everybody is guilty. It's just that we can't stop such thoughts from coming. Actually wrong. We can if we stop seeing reasons to go against God's plan and start applying the word of God in Proverbs 4:23. In fact the Christian race is not for the lazy type.

"And the peace of God which passeth all understanding, shall keep your hearts and mind through Christ Jesus", (Phil 4:7).

So what triggers unholy thoughts? There is a perfect answer � here on Bible reasons, https://biblereasons.com/sinful-thoughts/,the kind of music you listen to, and pictures formed from what you read or see - all acts as the pacesetter for devilish thoughts. And, doing away with devilish source of inspiration in conversations, movies( explicit ones that drives away the holy spirit away at clicking of the play button), and music as soon as possible keeps your heart more spiritual healthy.

So how can I be free?
There is no intellectual reasons that can set you free apart from reading the Bible(as our spiritual mirror) to know what sins that's potentially stealing God's peace from you, and hence preventing the peace from keeping your hearts as our text clearly stated.

Source: www.iinora.com