There’s an inner and external Christian life, the inner life is the way to attain true holiness and immortality in God. When Paul the apostle was writing to encourage Christians living in Corinthians in the 1st century, he said;
Therefore we do not lose heart. Even though our outward man is perishing, yet the inward man is being renewed day by day. For our light affliction, which is but for a moment, is working for us a far more exceeding and eternal weight of glory, while we do not look at the things which are seen, but at the things which are not seen. For the things which are seen are temporary, but the things which are not seen are eternal. (2Corinthians4:16-18)
This scripture absolutely explains what inner life in Christ represents. Inner life entails daily cleansing, purification of our inward man through the internal truth; the heavenly realities perceived through our inner sight or the eyes of the spirit. Inner life is the inward witnessing of the Holy Spirit (Romans8:16).
If you’re living an inner Christian life, or living by the Spirit you’ll discover that there are internal laws of God which can be hidden from a non spiritual person, because those laws aren’t written plainly in the bible. The law is only a shadow of the good things that are to come, not the realities themselves (Hebrews10:1-5). The law being the shadow of truth signifies that the written law has internal meaning and the internal meanings of the letter are more spiritual and influential than the written codes; for example, the written law says Thou shalt not commit adultery –(Exodus20:14). Now, a non-spiritual or a religious person can declare that he’s keeping this commandment perfectly based on the fact that he/she isn’t having physical sex outside of marriage, but the truth is that adultery is beyond that! Having sex outside of marriage is just one external aspect of adultery. Here’s an example, If a married man makes love to his wife and uses the face of his ex- lover or another woman, or a married women makes love with her husband and internally focuses in her mind on her ex or another person she was attracted to, that’s an advanced level of adultery. Jesus also said that anyone who even looks at a woman with lust has already committed adultery with her in his heart (Matthew5:28). This type of sin was pointed out by King David as secret sin…
WHO CAN UNDERSTAND HIS ERRORS? CLEANSE THOU ME FROM SECRET FAULTS. (PSALM19:12)
The letter kills, but the Spirit gives life (2 Corinthians3:6). One can keep all of the written laws just like the Pharisees, but internally the person still won’t be free from sin and guilt….
Woe unto you, scribes and Pharisees, hypocrites! For ye make clean the outside of the cup and of the platter, but within they are full of extortion and excess. Thou blind Pharisee, cleanse first that which is within the cup and platter that the outside of them may be clean also. Woe unto you, scribes and Pharisees, hypocrites! for ye are like unto whited sepulchres, which indeed appear beautiful outward, but are within full of dead men's bones, and of all uncleanness. Even so ye also outwardly appear righteous unto men, but within ye are full of hypocrisy and iniquity. (Matthew23:25-28)
This scripture is deeper than what most assume, you can maintain all that’s written in the bible and still not be clean before God, which is why you can’t judge who is a true Christian based on facial expressions or physical acts of kindness or doing good works, only God will judge the intent of our heart.