Being faithless describes a state where a person lacks the discipline and direction to follow Christ fully. The range of faithlessness may vary in degree from absolute atheism to simply needing guidance.
The difference between a faithless person and an atheist is that a faithless person has no strong belief in God whereas an atheist has no belief at all in God. An atheist is faithless, but a faithless person is not necessarily atheist.
Many people struggle with their Faith in God, due to the complexities of the universe and our human incapability to understand it. The way for a faithless person to rebuild their connection with God is to repent for their sin of not trusting him and to attend Mass to show they are willing to trust in God.
Lean not on your own understanding, but trust in the LORD with all your heart. -Proverbs 3:5
Examples of Faithless People
Here is a partial (but not exhaustive) list of some faithless groups of people:
Signs of Faithlessness
There are many signs to identify if a person is faithless or may not have a strong Faith in God. A person may outright declare their disbelief in God (in which case, one should try to direct the person back into Christ's arms); however, sometimes less subtle clues can indicate a person's shaky standing with their relation to God. Be on the lookout for some of the following signs.
Disregard for Sin
A person who disregards sin in entirety and leads a hedonistic lifestyle may be at risk of being faithless. For example, a homosexual does not care that his actions are sinful perhaps because he is not confident in the existence of God. Another such example is that people who use drugs disregard that "the body is a temple". Be on the lookout for violence, sex, and other Sin; as they may indicate one has lost their direction toward Jesus Christ.
Need for Proof of God
Many times one will try to reinforce their Faith by stating that there is undeniable proof of God. In reality, one is possibly unsure about one's Faith and is trying to make "logical" reasons to why their Faith is right. This is a dangerous part of faithlessness because the person is in denial about their disbelief in God. They will try to connect science to religion and find some trivial detail that somehow "proves" the existence of God. What they fail to realize is that one does not need proof for God: if one had Faith, they could believe in God despite all of the alleged "scientific" evidence to suggest otherwise.
Political Protest of Religion
Supporting doctrines like Separation of State and Church might be a cry for help. People who engage in political protest against organized religion may simply be starting to lose their Faith in God. Some claim they are religious yet do not wish to push their religion onto others; however, deep down they are trying to create a feeling that it is "okay" to question their Faith.
At the same time, you can still have faith and want separation of church and state as a National church has historically led to more liberal and faithless populations (See Europe)
This man is painfully faithless and perhaps incapable of repenting his Sins.
Not Attending Mass
Someone who does not go to Church regularly may be losing their relationship with God. Missing Mass is one of the first signs of faithlessness. Someone who does not attend Mass is not respecting God, perhaps because they refuse to believe in His existence. Usually, not attending Mass is a minor offense, but it may lead to greater grievances.