1 But realize this, that in the last days difficult times will come. 2 For men will be lovers of self, lovers of money, boastful, arrogant, revilers, disobedient to parents, ungrateful, unholy, 3 unloving, irreconcilable, malicious gossips, without self-control, brutal, haters of good, 4 treacherous, reckless, conceited, lovers of pleasure rather than lovers of God, 5 holding to a form of godliness, although they have denied its power; Avoid such men as these.2 Timothy 3:1-7 (NASB) (Read verses 6-7 on the site)
Observing unbelief in a professing Christian is a terrible thing. Unbelief, which is rooted in spiritual blindness, is deceitful. We must never forget that spiritual blindness is the product of idolatry. These nominal Christians never walk by faith. They make choices based entirely within a flesh-bound value system. This decision making process is part of self-worship. Their value system is based entirely within self-worth, self-focusedness, self-protection, et cetera. If they are religious Christians then their religion will be the same.