What does God say about a "Christian" who is deliberately sinning?
Here's some passages that come to mind
Paul is writing in 1 Corinthians chapter 6 to Corinthian "believers" who were suing, cheating and doing wrong to one another.
"The very fact that you have lawsuits among you means you have been completely defeated already. Why not rather be wronged? Why not rather be cheated? Instead, you yourselves cheat and do wrong, and you do this to your brothers." 1 Corinthians 6.7-8
So he then tells these "believers" not to be deceived. Deceived about what? That people who willfully sin will not inherit the kingdom of God.
"Do you not know that the wicked will not inherit the kingdom of God? Do not be deceived: Neither the sexually immoral nor idolaters nor adulterers nor male prostitutes nor homosexual offenders nor thieves nor the greedy nor drunkards nor slanderers nor swindlers will inherit the kingdom of God. And that is what some of you were. But you were washed, you were sanctified, you were justified in the name of the Lord Jesus Christ and by the Spirit of our God." 1 Corinthians 6.8-11
Note the "were". They no longer do it.
Quote from Life Application Bible commentary on this passage "Paul is describing characteristics of unbelievers. He doesn't mean that idolaters, adulterers, male prostitutes, homosexuals, thieves, greedy people, drunkards, slanderers or swindlers are automatically and irrevocably excluded from heaven. Christians come out of all kinds of different backgrounds, including these. They may still struggle with evil desires, but they should not continue in these practices. In 6:11 Paul clearly states that even those who sin in these ways can have their lives changed by Christ. However, those who say that they are Christians but persist in these practices with no sign of remorse will not inherit the kingdom of God. Such people need to reevaluate their lives to see if they truly believe in Christ." by Life Application Bible commentary
There is a huge difference between slipping occasionally and having a life style of "sexually immoral, idolaters, adulterers, male prostitutes, homosexual offenders, thieves, the greedy, drunkards, slanderers or swindlers". We can't judge a believer when they slip because we don't know their heart. But if the person is consistently sinning and is dominated (what they are thinking of most of the time) by the particular sin and where there is no repentance of it and asking for forgiveness and making the wrong right then that is what Paul is talking about. Maybe it's OK to take a fake brother to court. Remember that God will take care of all wrong.
What about believers who sin (we all do)
What to do when one sins? 1 John 1.9
What about a person who accepted Jesus and was baptized? He's doing sin against him. Is this a different level of sin? Will he be punished higher then another sin? Because isn't all sin equal. Or do we look at this one worse. How is it compared to if someone told a small lie once a day. I also understand the more obedient we are...we are blessed more.
He won't have prayer's answered? Or will he be put in fire? What is the ultimate consequence? Is he not saved now?