There are three things that happen when a person becomes a Christian. These are described in the Scripture , "Repent and be converted, that your sins are blotted out" (Acts 3:19. The first, "repent" is something that the person professing Christian has to do. The second and third "be converted, and sins blotted out" are what God in the person in response to the repentance.
Repentance is not merely putting on the "badge" of Christianity. It would just be a like a guy taking off his blue sports jacket, and putting on a red one. The jacket is different, but the man inside it hasn't changed. This is why we get some many professing Christians who may have got religion, and partially repented (holding on to their most enjoyable and favourite sins), but were never genuinely converted to Christ. It is one thing to accept Christ, it is quite another for Christ to accept the person. If a person hasn't fully repented - that is, turned from every known sin, and committed completely to Christ, then God holds back from doing the transformation work in the person in order to make them a genuine Christian.
People have mistakenly believed that walking up to the front of a church, praying a sinner's prayer and deciding to become Christian is actually genuine conversion. The truth is, only God can convert a person. The person cannot convert himself, and God won't convert a half pye religious person who has one foot in the church and the other in the world.
So, I reckon the "Christians" you have met, may still be unconverted, and not really of Christ at all, no matter how religious they are. When you meet a real Christian, who is all for Christ, absolutely strict in following Christ's laws. loving God with all his heart and loving you as he would himself, and has been fully transformed by the work of the Holy Spirit within them, you will know it beyond doubt. You may not like the level of their commitment, or their strictness in living a holy life, treating the world as if they are in it but not of it, but you would not be able to deny that there is something significantly different about them. You would either be repelled and want to keep away from them because they make you feel bad about yourself; or you will be drawn to Christ and say from your heart, "What shall I do to be saved?"