Transforming prayer into routine is considered a sin because it turns living communication with God into a mechanical repetition of words without genuine heartfelt involvement.

Revitalizing Prayer: From Routine to Heartfelt Communication

Transforming prayer into routine is considered a sin because it turns living communication with God into a mechanical repetition of words without genuine heartfelt involvement. Such prayers lose the power of reverent awe, which can enliven the soul, fortify the spirit, and even heal the body. As noted in one source, when we pray out of habit, with our mouths and not with our hearts—"without heartfelt contrition, without a firm desire for correction"—we risk incurring God’s wrath, as our act becomes merely a formal compliance with a rule rather than a true connection with the Lord ( link txt).

To preserve the true meaning of prayer, it is necessary to consciously strive for sincerity and to be fully immersed in each spoken word. It is important that the heart is tuned to communicate with God; only then will prayer cease to be faceless and routine. For instance, one text emphasizes that "every word" should be remembered and that one must pray with honesty, showing deep attention to one’s thoughts and feelings ( link txt). This approach not only prevents the superficial performance of religious duties but also transforms worship into a source of joy through the Holy Spirit and a grace for the body.

Moreover, another source clearly points out that prayers should be regarded as profound and meaningful texts rather than mere formal rituals: "These prayers are very deep and full of meaning. And the reading of them should never turn into formality, routine..." ( link txt). Thus, to prevent prayer from devolving into an empty routine, it is crucial to focus on its meaning, strive to be moved by every word, and make a concerted effort that prayer reflects a sincere spiritual need.

In summary, the sin of performing prayer mechanically lies in the lack of true inner involvement. The key steps to preserving its authentic meaning include:
1. Striving to pray not out of habit, but with sincere heartfelt contrition.
2. Attentively reflecting on every prayer phrase and word.
3. Continuously working on the soul so that prayer becomes a living communication with God, rather than a formal obligation.

Supporting citation(s):
"How terrible is the deception and how grievous the sin! Involuntarily, one recalls the Lord's severe words to His negligent doers: cursed is everyone who performs the work of the Lord with carelessness!... They pray daily, perhaps for long periods—praying out of habit, with their mouths rather than with their hearts, without heartfelt contrition..." (source: link txt)

"These prayers are very deep and full of meaning. And the reading of them should never turn into formality, routine..." (source: link txt)

"The heart should enter the temple moved by the experience of confession: ... one should be honest and quietly ask for help." (source: link txt)