Why is the index finger not used for chanting garlands, havan and applying tilak?

Puja Path Niyam: In Sanatan Dharma, many rules have been given regarding worship. If havan, worship, chanting, recitation etc are done in the right way only then it gets its full fruit. 

Havan Pujan Jaap me Tarjani finger ka upyog: Havan, worship, recitation, mantra chanting etc. have been given a special place in Sanatan Dharma. These things take us closer to God. Brings positivity, happiness and prosperity in life. To get full results of doing these auspicious works, it is necessary that they should be done in the right way. Some rules should be kept in mind while worshiping, reciting, chanting mantras, havan etc. For example, perform worship rituals in auspicious time, use the right method etc.

Mantra chanting, don't use index finger in Havan 

One such rule related to worship is that the index finger should not be used in offering Havan, chanting mantras or applying Tilak. Using the index finger in these works is considered inauspicious. Index finger is called index finger in English. This finger is the first finger after the thumb. 

Actually the index finger shows the ego of the person. Generally a person uses the index finger to show his ego and power. Along with this, the index finger is also used to blame others, to insult someone. Since the purpose of religion, worship, recitation, mantra chanting is that a person leaves the ego and goes closer to God. He should worship God with a calm mind and no negative feelings of his mind should become an obstacle in this. That's why index finger is not used in such auspicious works. 

The index finger is shown only to the enemy. That's why it is considered inauspicious to use the index finger while applying Tilak. Applying Tilak is a symbol of respect, so it is considered auspicious to apply it with thumb and ring finger.