But the title is negative, not positive: why? The reason lies in the simple fact that knowledge of the doctrines of the Church alone is not enough: while it is good and necessary to know the orthodox faith, obedience to it automatically becomes a requirement - this is something that not few fail to realize. There are enough who study a lot and debate a lot the issues of morality, faith and Church discipline as though they were merely theoretical ideas. But what about the number of those who actually try to live according to what they learn about Sacred Truth?
In that sense, there seems to be a problem which turns the Christian faith - which is meant to captivate the whole person - to a merely theoretical construct which is "nice to discuss", but is left in the realm of abstract ideas: it is thought of, but not lived. A person who knows the Truth, but does not live accordingly will be left without excuse. It does not suffice to "know" doctrine, one must live by it.
(James 1:) 22 But be ye doers of the word, and not hearers only, deceiving your own selves. 23 For if a man be a hearer of the word, and not a doer, he shall be compared to a man beholding his own countenance in a glass. 24 For he beheld himself, and went his way, and presently forgot what manner of man he was. 25 But he that hath looked into the perfect law of liberty, and hath continued therein, not becoming a forgetful hearer, but a doer of the work; this man shall be blessed in his deed.
26 And if any man think himself to be religious, not bridling his tongue, but deceiving his own heart, this man's religion is vain. 27 Religion clean and undefiled before God and the Father, is this: to visit the fatherless and widows in their tribulation: and to keep one's self unspotted from this world.
The more a person knows, the stricter are the standards, the less the excuses. One must therefore know what the reason for such religious studies ought to be: the deepening of one's living relationship with God. If one studies these things for the sake of winning debates for vainglory, then indeed such knowledge is sin, for it does not lead to God, but away from Him: it is knowledge without wisdom.
It is of course much easier to tell others how wrong they are and what they ought to do than to correct one's own lifestyle.
But in this case, the words of the Lord apply perfectly:"Thou hypocrite, cast out first the beam in thy own eye, and then shalt thou see to cast out the mote out of thy brother's eye." (Matthew 7:5)
The reason and end of one's religious studies must be God,
The reason for one's preaching must be charity, not personal fame.
Obedience to God through obedience to His Church and humility help us stay on the right path: those who are vain and prideful go astray.