Can one overcome in this life the effects of bad karma (action) in past lives, or will it take several lives?
If all the windows of a room have been closed and the light shut out for a hundred years, and then, one day, suddenly the light is allowed to enter, there will no longer be any darkness, of course. Obviously, therefore, we cannot say that it will take one hundred years to bring light into the room just because the room has been dark for one hundred years.
In the same way, the darkness of ignorance, or the effects of evil actions in the form of concentrated mental tendencies, might reign in the soul for hundreds or thousands of years. But as soon as the light of God-contact comes, all the darkness of that karma is dispelled.
God is not vengeful. Just because a person has been in ignorance for one hundred years does not mean that he will have to work for another one hundred years, over the course of more than one lifetime, to work out the karma accrued over one hundred years of ignorance. If a person is determined enough, and meditates a great deal, he can destroy the bad karma of all his past lives in a single lifetime.
We are all made in the image of God, and we are all eternally the same as God. Ignorance is not our true nature. Ignorance is the result of the soul’s misuse of free will, and can be removed instantly, or within a few years, by the right teaching, meditation, and dedicated spiritual living.
The early settlers in America had no other conveyance except covered wagons. They reasoned that crossing America from one coast to another would require six months or a year. They would have laughed if someone had told them that in 1939, the country would be crossed in twelve hours by airplane.
Paramhansa Yogananda brought to the West teachings and scientific techniques that quicken our spiritual evolution. Meditation is the most important of these techniques. The fire of regular, deep meditation cauterizes the brain grooves which contain the records of bad karmic tendencies from past lives, and thus overcomes their hidden evil. By regular, deep meditation and right living, it is possible to overcome the bad karma of many past lives in a single lifetime.