Can any god among 330 million Hindu gods save a sinner and make him/her holy? Please give references from Hindu Scriptures. (Not your own version as a Hindu but quotation from an authentic religious book.)
The only thing that can for sure remove all the sins committed by a person is Sharanagati, Surrendering to the Lotus feet of Lord Shriman Narayana.
Shrimad Bhagwad Gita Chapter 18 verse Shloka 66
सर्वधर्मान्परित्यज, मामेकम् शरनम् व्रज । अहम् त्वा सर्व पापेभ्यो मोक्श्यामि मा शुच
Completely relinquishing all Dharmas, take refuge in Me alone. I will release you from all sins, grieve not.
Translating word by word
'Relinquishing all Dharmas’ means the complete abandonment of the notion of agency, proprietorship, results etc., in the practice of Karma, Jñāna and Bhakti Yogas which are the means (dharmas) for attaining the highest good when done as Divine Service.
'I will release you from all sins' means that I will free you from all obstacles that prevent you from attaining Me; consisting of [the karmic reaction of] innumerable acts of doing what is forbidden and neglecting what is bidden. Accumulating from beginingless times [the reactions of] these deeds cause obstacles in spiritual development.
Alternative Interpretation Bhakti Yoga is possible only for those individuals who love the Lord intensely and who are free from all negative karma. One’s karmic reactions (sins) are obstacles in the path of developing loving devotion and are so numerous that the expiatory rites which would exculpate them could not possibly be performed in the limited time of one life span. Arjuna therefore thought that he was incapable of practicing Bhakti Yoga. To remedy Arjuna's despondency the Lord said: 'Completely relinquishing all Dharmas, take refuge in Me alone.' The term ‘Dharma’ used in this context would apply to the expiatory rites. So in order to successfully commence Bhakti Yoga, surrender to Me alone. I am supremely compassionate, the refuge of all without distinction, an ocean of maternal solicitude for those dependent on Me. I will release you from all sins, which have been explained as obstacles to the practice of Bhakti Yoga — grieve not.
As TheDestroyer mentioned you have to be completly loyal to yourself and god,you should feel guilty for committing those sins, then and only then there is meaning to sharanagati, you should love Shriman Narayana who is supreme bramhan or love nirguna bramhan if you think advaita is correct