Bhagavad Gita : Chapter 17

Arjuna:
Krishna, now what will happen to those who act in faith, but not in accordance with scientific teachings? In which category do they belong, satvic, rajasic, or tamasic?

Krishna:
There are three types of Faith, depending on individual nature, satvic, rajasic and tamasic. Everybody's faith is in accordance with his particular nature.

A person is what his faith is. If his faith is of a particular kind, that type he would be.
Satvic people worship devas, rajasic worship yakshas and rakshasas, tamasic worship ghosts and spirits.

Those who do terrible penances not prescribed in shastras, and full of haughtiness and egotism, senselessly weaken all beings and also ME residing in their own bodies, are of asuric nature.

Food is also similarly of three types, so is sacrifice, and offering of gifts; hear how they are different.

That food is preferred by satvic people, which promotes life, energy,strength, health, pleasure and appetite, and which is tasty, juicy,palatable and not easily spoiled.
And rajasic people like food which is bitter, salty, very hot, sharp, spicy and burningly pungent, and which causes discomfort, aches and diseases.
Food liked by the tamasicis cold, dry, smelly, stale and unclean leftovers.

The sacrifice, performed as a duty worth doing, without desire for result, and in accordance with the rules, is satvic.
Done with the desire for results, or for ostentation, it is rajasic.
The sacrifice done carelessly and without any rules, without mantras, and without feeding of the deserved, without paying for services, is tamasic.

Paying respect to gods, Brahmins, teachers, and other wise men,cleanliness, integrity, abstinence, and nonviolence constitute bodily penance.

Inoffensive, honest, pleasing and helpful speech, and study of holy texts, constitutes oral penance.

Cheerfulness, benevolence,silence, self-control and purity of feelings constitute mental penance.

The threefold penance is called satvic, if it is performed with full faith, and with no desire for result.
The penance done to get honours and approval, and out of pride, is what is called here rajasic.
That done with ignorant expectations and self-torture, or for hurting others is said to be tamasic.

The gift given as one's duty to a deserving person, who has not done anything for you, at proper time and place, is considered satvic.
That done reluctantly with expectations of return or for some other result is rajasic.
That given to the undeserving, at wrong time and place,unwelcome, and disregarded is tamasic.

Om, Tat, and Sat are the three accepted symbols of Brahma; brahmins,vedas and sacrifices are from old covered by them.

Therefore the sacrifices, offerings, penances, stipulated in scriptures, are always performed by the adherents of vedas with the word "Om."

Those, who seek liberation, perform the various types of sacrifices,offerings and penances, without regard for results, and say the word"Tat""Sat" is used in the senses of both real and good, as well as to indicate worthy deeds.

Performance of sacrifices, offerings, and penances are all therefore called sat; so also all acts to further them.

And all this done carelessly and without faith is called "asat"; with such no use here or in the other world.