If this birth is based on the deeds of our previous life, then our destiny is pre-determined. So, there is no need for god unless prayer offered to him will erase the bad deeds.
Prayer, PujA (worship) etc can remove sins committed in infinite number of our past lives.
Here is a proof that prayer in the form Mantra Japa can do it:
Lakshyadwayen pApAni saptajanmakritAnyapi |
NAsayet TripurA devi sAdhakasya na samsayaha ||
JaptvA lakshyatrayam mantri yantrito mantra vigraha |
PAtakam nAsayedAsu yadi janmasahasragam ||
[Lord Shiva said] If the devotee does japa [of the mantra] two lakh times, Goddess TripurA will destroy all his sins that was accumulated in his past seven lives. And one who does japa of the mantra three lakh times, becomes himself the personification of mantra and yantra and destroys thereby the sins that he has accumulated over his past thousand lives within no time.
NityAshodashikArnava Tantram 5-11,12
Here is a proof that prayer in the form of Stotram can do it:
Sourashtre Somanadham, cha Sri Shaile Mallikarjunam, Ujjayinyam Maha Kalam, Omkaram, amaleshwaram, Paralyam Vaidyanatham, cha Dakinyam Bhimasankaram, Sethubandhe thu Ramesam, Nagesam thu Darukavane, Varanasyam thu Viswesam, Trayambakam Gouthami thate, Himalaye thu Kedaram, Ghushmesam cha Shivalaye, Ethani Jyothirlingani sayam pratha paden nara, Saptha janma krutham papam smaranena vinasyathi.
The twelve Lingas of light are, Somanatha in Sourashtra, Mallikarjuna in Sri Shailam, Mahakala in Ujjain, Omkaram in Amaleshwara, Vaidhyanatha in Parali, Bhimasankara in South, Rameshwara near the bridge in Sethu, Nageswara in Daruka forest, Visweswara in Varnasi, Trayambakeshwara in the shores of Godavari, Kedareshwara in Himalayas, And Ghushmesha in Sivalaya. He who remembers them, Morning and evening, Would wash away sins, committed in his seven births.
The Dwadasa Jyotirlinga Stotram
And, here is a proof that prayer in the form of Puja (worship) can do it as well:
MahApAtakayuktAtmA yadi Devim prapujAyet |
MAsen hanti kalusham saptajanma kritam naraha ||
[Lord Shiva said] The devotee who (even if he is afflicted with mahApatakas or great sins) worships Devi with the leaves of Sami, DurvA, Aswattha or Arka plants destroys thus his sins accumulated over his past seven lives.
NityAshodasikArnava Tantram 2-66
And, in the commentary of this verse Acharya ShivAnanda interprets the word saptajanma as to mean infinite number of past lives. Usually in such verses the words such as sapta (7), sata (100) or sahasra (1000) are to be interpreted to mean numerous or infinite rather than just a specific number.
Repeating the name of God is very effective in lessening the effects of past deeds.
Sri Sarada Devi:
One has to suffer the consequences of one’s deeds. But by repeating the Name of God, you can lessen its intensity. If you were destined to have a wound as wide as a ploughshare, you will get a pin-prick at least. The effect of Karma can be counteracted to a great extent by Japa and austerities.
As I am a devotee of Rama, I will be elaborating on the supreme infallibility of Naam Japa (name chanting), especially of Lord Rama.
Rama Nama gets exactly the same importance in Saguna Upasana (worshipping the Absolute Truth as a Being with a form) as does the Pranava ('Om') MantrainNirguna Upasana (worshipping the Absolute Truth as formless).
Rishi Manu shows that the Rama Nama has links to all the other mantras that ever exist.
In Syavana Smriti (Syavana is the name of a rishi), Syavana says that the Rama Nama is the essence of all the Vedas, Shastras, Itihasas and Puranas.
Sage Vasishta meditated on the Rama Nama for quite a long time. Hence he wanted to name the Almighty with the same Mantra that he had chanted.
RELIEVES PLANETARY EFFECTS: Once you start believing in Rama, you should never believe on any propaganda of Planetary systems. Planets are there in the Universe to perform their role but not misguide you. Even if you are suffering from malefic effects, Ram naam is your only savior. Remember, at the end Karma will bite you for your wrong doings and planets are a readable medium for discernment. Ram naam can only divide the problems so that you can handle it better. But it will be always there. If you love God, then you should have no reason to fear.
The 'sthala purana' of Kasi says that the deity Kasi Viswanatha initiates the Rama Nama to each and every being at the time of their death, in their right ear.
Shiva on the other hand mentions to Parvati:
Rama rama rameti rame rame manorame
sahasra nama tat tulyam rama namo varanane
“O dear wife, Parvati, one thousand names of Visnu (another name of Narayana) are equal to one name of Rama and three names of Rama are equal to one name of Vishnu."