Answer

In Jain Dharma, fasting is traditionally dedicated to self-purification, restraint, karma-nirjarā, and spiritual progress—not to pleasing or worshipping a creator god.

If, as a Jain, you fast on Monday with devotion to Mahadev, it is important to understand that this is not a standard Jain practice, but rather a devotional practice connected with Hindu tradition.

Explanation

Jain fasting such as:

• Upvas
• Ekasana
• Ayambil
• Beasana
• Chauvihar
• Paryushan / Das Lakshan tapasya

is practiced for:

• Reducing attachment to the body
• Controlling desires
• Practicing ahimsa and self-discipline
• Destroying accumulated karma
• Developing equanimity and inner purity

Jain Dharma does not teach dependence on divine grace for liberation. Liberation comes through:

• Samyak Darshan — right faith
• Samyak Jnan — right knowledge
• Samyak Charitra — right conduct

Spiritual Understanding

If you wish to keep a Monday fast while remaining aligned with Jain Dharma, you can dedicate the fast to:

• Ātma-shuddhi — purification of the soul
• Ahimsa — non-violence
• Samyama — self-control
• Remembering Arihant Bhagwan, Siddha Bhagwan, Acharya, Upadhyay, and Sadhu
• Reciting Navkar Mantra
• Doing pratikraman, samayik, swadhyay, or meditation

You may respectfully hold personal devotion, but from a Jain perspective, the highest spiritual focus is on the liberated souls and the path of liberation, not on worldly powers or creator deities.

Takeaway

As a Jain, fasting is most spiritually beneficial when done for self-discipline, karma reduction, and soul purification. If you fast on Monday, try to make it a Jain tapasya by connecting it with Navkar Mantra, samayik, pratikraman, swadhyay, and inner detachment.