Being faithful is not about being without sin (impossible), it's not about being without error doing everything perfectly, it's not about being the most holier than thou person you can be, it's not about putting up a show for the world/ others/ anyone to see how good and "Christian" you are (neither is it about putting up a show of praising self about how 'low' you are compared to God, as in look at me I am so humble, that's disguised pride too). But being faithful is all about YOU being being faithful to God in YOUR walk WITH Him, it's about knowing/ being aware that you will give an account of yourself to God (Romans 14:12). It's about wanting to please Him and trusting in Him, to listen to the Holy Spirit working in you, to learn from Christ His stewardship and ministry here on earth, to then also be faithful in your walk with God and be faithful with the stewardship that God has given you in your life.
It's not about doing great works of your own or about being perfect or without error, but it's about being faithful to God, to listen and follow His Holy Spirit. The people losing out on the inheritance of entering the Holy land was not about being sinners or not, or about doing great works or not, it was all about a lack of faith in God. They did not yield to God but instead grumbled against Him, placing bad attributes on God and blaming Him. Their lack of faith resulted in them losing out on their inheritance, having to stay in the wilderness. Even to the point of saying that they were better of as slaves in Egypt than to walk in the wilderness with God. And it's easy for a believer today to say; that's blasphemous I would never say such things. But through our actions and in the things we say, we too are guilty of lack of faith in God. Do we pray FOR someone or against someone? Do we blame God or do we thank and praise Him? Do we accept tribulation/ hardships and all that God places in front of us (including people that oppose Christians) or do we try to fight against it in hopes that it goes away? Do we accept corrections and training by the Holy Spirit or do we walk away from it? And being faithful or not is not about being saved or not. It's about obtaining the inheritance or not. It's about every believer who can be a 'son who inherits' (it's not about physical males and not about literally being firstborn in your family, it's a type). It's about heirs who are in bootcamp training here on earth, wanting and trying to be faithful to God. In opposite of faithless believers who lose out on the inheritance because this life, world and self is all that matters.
Faithless people do not really care about what God wants and do not really care if they please Him or not, this is not on their mind and this does not worry them. It's mostly about their own world and their own lives having their mind not set on God and the things He wants. Maybe for some their mind is set on Him on a sunday morning but that is all the time/"investment" that they can spare/ give to Him. Eventhough faithfulness is not an exact measurement, you could say that for a faithful Christian their mind is set on God >wanting/ trying< to please Him (by faith). Which does NOT mean you are without sin, or without temptations, or without error, or without the strings of the world pulling on you, or without earthly/ fleshly desires, it does not mean your works are great, and does not mean you have to quit your job and be studying the Bible 24/7 or be in ministry 24/7. The difference is faithless people do not really care about God and what God wants, it would probably even be a nuisance because God is then standing in the way of all the things they want, or the things God wants are too much trouble or too difficult in their eyes to then walk away from God and the things He wants. God is just a small part in their lives when it's convenient and/ or when it's easy and do not yield to His Spirit and the teachings, training and corrections of the Spirit.
Some today will be busy with the world and themselves to then have some kind of sunday social spiritual "detox" morning/ day to then, again, turn their focus away, turning back to everything else but God. The most time you spend with God should be outside the church, being a day to day thing. If the only time you have your mind set on God is on a sunday morning, then it is time to take your walk more serious. And again, a walk with God is not about your great works and spending time with Him does not mean you have to be reading the Bible all day long or be in ministry 24/7, it's about following His Holy Spirit, yielding to it and it's teachings, training and corrections, by keeping the faith (even more when things get rough, to not walk away and give up), not blaming God, not placing bad attributes on Him. If you are faithful you will enter this tug of war "fight" and keep trying to run the race until the end, and that faithfulness to Christ is a day to day thing, in all choices you make, in all things you say, in all things you do (again not saying/ meaning you are without sin or without error or without mistakes). And if faithless believers truly came to Christ at one point, they will still be saved.
Besides being faithful to Gods Spirit (to His teachings/ training/ corrections in/ on you), every person has a stewardship that differs from person to person, so I cannot tell you what God has given you in your life to take good care of. It's not about everyone having to be a pastor, or being in ministry, or being a missionary in a foreign country, or being a street/ online evangelist (these things CAN of course be your calling and be part of your stewardship, and if it is, do yield to it), there are many more things God can give/ has given you to take good care of; people (family, spouse, children, colleagues, classmates, customers, neighbours, etc, can be anyone), pets, (free) time, work/ job, even money (not the love for it, not personal profit of it, but money can/ should be used for good instead of just personal pleasure, Joseph is a good example of a good steward, stewarding Pharaoh's possessions, God can give you wealth to use for good), skills, gifts, spiritual calling(s), wisdom, and so many many more things that you can take good care of, as God has given it to you, as a steward over Gods possession(s) here on earth.
For example: do you take good care of your spouse, of kids, of colleagues, of classmates, of friends, strangers, pets etc. Take good care of everything in your stewardship as Christ did, having Him as your example, being kind, being humble, loving, caring, showing mercy, showing grace, serving, helping out. And it's not about others deserving it or not. And it does not have to be grand things, even things like taking good care of your pets. They all are part of Gods creation and are Gods possession and can be part of your stewardship, as God placed them in your care, in your stewardship. How many parts of Gods creation (including pets) get treated horribly, when you love and take good care of your pet(s) and make sure it's needs are fulfilled all the way until the end, to the best of your ability with the resources that are available to you, then you are a good steward regarding this part of your stewardship, and you are taking good care of the possession God entrusted you with. It's not always easy or straightforward but there is caring, trying and coming short. And there is not caring about the things of God because it's all about self and own wants.
And stewardships can therefore also change over time, people come people go, pets come pets go, different callings can come later on in your life or when you are further in your walk with Chirst. For example, when it is time for a pet to go, maybe after a while you feel the Holy Spirit calling you to take in another pet, it wouldn't be a replacement, but it then becomes a change in (and part of) your stewardship, who then needs your care and is dependent on you to take good care of it. Or maybe you feel the Holy Spirit calling you to another path, to another task, or maybe you feel a call for multiple tasks. Therefore it is important to pray about all things and ask God what He wants from and for you, to ask for His will to be done, and to then listen to His Spirit and step into the 'works' that God lays out in front of you. Sometimes it can take a while before it becomes clear and get an answer. Sometimes God simply wants you to be 'sitting in the waiting room' and be ready 'to go in' when called. For example maybe the pet God wants you to take good care of, and has been appointed by Him to you and your stewardship, simply has not been born yet, or is not ready yet, or has not reached the point yet for you to take over/ step into, or maybe you are the one who is not ready yet for a specific task God wants you to do in the future, maybe God is doing some work on you to prepare and make you ready for a future task. Whatever it is, pray about it and lay it at Gods feet and follow His Spirit, His instructions.
We all are going to give an account of ourselves to God, about how we lived our lives, things we say/ do not say, things we do/ not do, how we treated others, things we did/ didn't do regarding our faithful walk with God and the stewardship we had (for believers; this is not a judgement about salvation, this is about rewards (by faithfulness) and inheritance (by submission to, and sanctification by, the Holy Spirit, yielding to His training and corrections, not walking away from it). And the important thing about this is, God is not looking if you did everything completely right and without any error or mistakes, what matters is the condition of your heart and mind; did you care? did you try? did you care about God and the things He wants? did you try to take good care of the things God gave you? did you try to take good care of the things God entrusted you with? did you try to yield to His Holy Spirit when it trained and corrected you?
And we all come short, we all stumble, we all fall, we all make mistakes, we all can do more, we all can do better, and we all commit sin. But we confess to God, ask forgiveness and help, and then get back up and run the race again. People for example who are just and only sunday Christians and are (for the rest of the week/days) busy with the cares and pleasures of this world, may actually be saved and be sealed by the Holy Spirit (God only knows). If at one point in their life they came to Christ they will (how lukewarm they may be) still be saved, but they are in danger of losing out on rewards and/ or inheritance.
Again, that's different from being saved/ salvation, it's not about working out your own salvation, it's not about own righteoussnes, it's NOT. It can be compared with marriages, as the day of the wedding is not the end all be all what marriage is all about, in fact, the wedding is the start of a lifelong marriage, of a faithful walk with your spouse, a walk whereby everyday you choose and stick with your spouse, same as coming to Christ and being sealed by Gods Holy Spirit is the start of your faithful walk with God, to then choose God day by day, trusting in Him, sticking with Him, submitting to Him. The lukewarm and faithless can be compared to a human marriage as well, as someone who takes and lives just for him/ herself within a marriage, not giving a thought about their spouse and not living out marriage as an unified couple, but just lives for self and for gain, again, that's different from trying and failing and not doing and not being perfect, so don't judge and 'kick down' your spouse for imperfections or for failings, instead encourage and guide/help him/her, and also encourage and help each other in your walk with God.
But for the faithless it's not too late to turn around and take your walk more serious. To take your walk of faithfulness to God and being faithful with your God given stewardship here on earth more serious. And as long as you are living it's never too late to turn to God and say; God, guide and help me in my faithful walk and in my stewardship here on earth. As God will provide, He will give/ guide/ help you in all that you need in order to please Him by faith. In your relationship with God, He will lead, He will guide, He will provide. And you submit to Him, stick to Him, and follow Him, in faith(fulness) and by submitting to your God given stewardship and trying to be a good steward over it.