If you become a Spirit-filled Christian, you become a righteous person, meaning being in the right standing with God. That is good. That is what God wants us to be, more of Him, who is spiritual, and less of us, who is more worldly than spiritual.
He must become greater and greater, and i must become less and less. John 3:30
When the moment someone starts making comparisons and thinks that someone is more spiritual than others, puffed up based on what he/ she knows, (just as what Paul warned us in Phi 2:3, not to be selfish or try to impress others but be humble, not to think of yourselves as better than others) this is the moment being spiritual is derailed into the track of self-righteous.
Self-righteous means thinking that one is always right according to his own judgement, his decision is always better than others, he does not need to consult others. What happens is, someone becomes more self-righteous, NOT SPIRITUAL. Yes, it can even happen during spiritual growth, if one is not careful. It is an issue of pride in life. We shall keep the word ‘spiritual’ divine, pure and Godly, without blames, blemish and contamination. Meaning you can become more spiritual but careful not to tread on the path of self-righteousness. To some, between being spiritual & self-righteous are separated by a thin line. The line may appear very blur to some. A misstep could lead to spiritual death. So do not be confused with someone being too spiritual from being self-righteous. It is not wrong to be too spiritual, but it is a sin to be self righteous. Being too spiritual will not neglect or forget about reality. They will still keep their feet on the ground, meaning they still have a sensible and practical attitude towards life, according to God.
Many Christians are confused because some words have not been preserved or understood correctly. Instead, contaminated and misunderstood out of context.
Man has the tendency towards believing the negative words than the positive ones, perhaps, to protect themselves and to survive, and prepare for the worst. Watch out, our mind can be so easily skewed away from God’s way of thinking. God has a solution for you.
For God has not given us a spirit of fear and timidity, but of power, love, and self-discipline.
2 Timothy 1:7 NLT