Q. It is said that our destiny has already been written and we are totally under the control of three modes of nature. Not even a single leaf can move without Krishna’s will. So how is it that we become responsible for the sinful or pious activities that we perform?
A. Our destiny is written based on our previous karmas. Now, if we continue to perform the sinful actions then accordingly, we will get the results in future. This way, we are responsible for our own sinful activities. We can not blame anyone. Best thing is akarma.
Bhagavad Gita 3.5:
na hi kascit kshanam api
jatu tishthaty akarma-krit
karyate hy avasah karma
sarvah prakriti-jair gunaih
Everyone is forced to act helplessly according to the qualities he has acquired from the modes of material nature; therefore no one can refrain from doing something, not even for a moment.
It is not a question of embodied life, but it is the nature of the soul to be always active. Without the presence of the spirit soul, the material body can not move. The body is only a dead vehicle to be worked by the spirit soul, which is always active and cannot stop even for a moment. As such, the spirit soul has to be engaged in the good work of Kriishhna consciousness, otherwise it will be engaged in occupations dictated by illusory energy. In contact with material energy, the spirit soul acquires material modes, and to purify the soul from such affinities, it is necessary to engage in the prescribed duties enjoined in the sastras. But if the soul is engaged in his natural function of Kriishhna consciousness, whatever he is able to do is good for him. The Srimad-Bhagavatam (1.5.17) affirms this:
tyaktva sva-dharmam caranambujam harer
bhajann apakvo ‘tha patet tato yadi
yatra kva vabhadram abhud amushya kim
ko vartha apto ‘bhajatam sva-dharmatah
“If someone takes to Krishna consciousness, even though he may not follow the prescribed duties in the sastras or execute the devotional service properly, and even though he may fall down from the standard, there is no loss or evil for him. But, if he carries out all the injunctions for purification in the sastras, what does it avail him if he is not Krishna conscious?” So, the purificatory process is necessary for reaching this point of Krishna consciousness. Therefore, sannyasa, or any purificatory process, is to help reach the ultimate goal of becoming Krishna conscious, without which everything is considered a failure.
Also, BG 4 TEXT 18
karmany akarma yah pasyed
akarmani ca karma yah
sa buddhiman manushyeshu
sa yuktah kritsna-karma-krit
One who sees inaction in action, and action in inaction, is intelligent among men, and he is in the transcendental position, although engaged in all sorts of activities.
A person acting in Krishna consciousness is naturally free from the bonds of karma. His activities are all performed for Krishna; therefore he does not enjoy or suffer any of the effects of work. Consequently, he is intelligent in human society, even though he is engaged in all sorts of activities for Krishna. Akarma means without reaction to work. The impersonalist ceases fruitive activities out of fear, so that the resultant action may not be a stumbling block on the path of self-realization, but the personalist knows rightly his position as the eternal servitor of the Supreme Personality of Godhead. Therefore, he engages himself in the activities of Krishna consciousness. Because everything is done for Kriishhna, he enjoys only transcendental happiness in the discharge of this service. Those who are engaged in this process are known to be without desire for personal sense gratification. The sense of eternal servitorship to Krishna makes one immune to all sorts of reactionary elements of work.
So, we are responsible for our sinful or pious activities that we perform.