Not reading the Bible certainly leads to spiritual weakness in born again believers in the Lord Jesus Christ. Perhaps surprisingly, however, reading the Bible can do the same.
The former point is obvious. "Faith cometh by hearing, and hearing by the Word of God" (Romans 10:17). Our Heavenly Father communicates Himself and His truth to us by Scripture. If, therefore, we have access to the Bible and the capacity to read it (or in our generation, to listen to recorded versions), we can be sure the Holy Spirit will lead us to consistently expose ourselves to the light of His written Word. "Strengthen Thou me according unto Thy Word" (Psalm 119:28).
There is nevertheless an inherent danger in consistent reading of Scripture, namely, that we perceive the mere reading and study of Scripture as an end in and of itself. Indeed, the Bible teaches that there is no merit in the consideration of its holy pages. There is advantage, but not merit.
"Be ye doers of the Word and not hearers only, deceiving your own selves" (James 1:22).
"What advantage then hath the Jew?... Much every way: chiefly, because that unto them were committed the oracles (utterances) of God" (Romans 3:1-2).
Simply knowing or even memorizing the Bible provides no guarantee that we will trust and obey the Bible. In fact, our spiritual enemies are not hesitant to use this practice as a means of deception. Recall that Satan wielded Scripture in the wilderness temptation in his attempt to fell even the Lord Jesus Christ (a profound devilish mistake, of course). How much more will our foe seek to tempt us in the same way?
Pride will likely be his primary attack upon us. Suppose, for example, we determine to read the Bible daily, a fine and good practice. On the first day, we do so. If we could hear our enemies audibly, a whisper might light upon our ears, "Hmm, read your Bible today? Good, very good." If a week of Scripture reading finds us diligent and faithful, "Seven days in a row, eh? That's something!" Or a month - "You've read the Bible every day for a month? Impressive!" And, if a year, well, you get the point. Again, we don't hear the audible voices of our enemies, but they do seek to tempt us with attitudinal promptings to think well of ourselves because we've been a consistent hearer of the Word of God. And that's the rub. If thinking well of ourselves because of consistency and perceived discipline results from Bible reading - and it can - time in the Scriptures can actually set us back a long, long way. Or rather, our fleshly attitude toward the Scriptures can become a hindrance in our walk with God.
This is no suggestion that we refrain from consistent reading of Scripture. Far from it. Still, we must be aware that our spiritual enemies seek to tempt us with good things, and even with perfect things. Yes, the devil can deceive us with Truth misinterpreted, misapplied and misunderstood if we are not aware of his subtle and skilled weapons of error. "Account that the longsuffering of our Lord is salvation; even as our beloved brother Paul also according to the wisdom given unto him hath written unto you; as also in all his epistles, speaking in them of these things; in which are some things hard to be understood, which they that are unlearned and unstable wrest, as they do also the other Scriptures, unto their own destruction" (II Peter 3:15-16).
How do we overcome the temptation to view hearing the Word as synonymous with doing the Word? Remembering that we would have no interest in the Word at all apart from God's gracious work in our hearts and minds greatly helps us to avoid the deception of pride. Certainly we respond to His working in us to expose ourselves to the Scriptures. But it is response. We do not initiate interest in the Bible, or the active steps to open and peruse its pages. We rather act as the result of the Holy Spirit's acting upon and within us to consider His Word. "O send out Thy light and Thy truth: let them lead me; let them bring me unto thy holy hill, and to thy tabernacles" (Psalm 42:3). Thus, the only merit in our reading of Scripture is the glory we directly wholly and solely unto the God who delights in communicating Himself and His truth to us...
"I have taught thee in the way of wisdom; I have led thee in right paths."