The generosity of Allah Almighty is limitless. He opens His doors of forgiveness and rewards to anyone who seeks Him sincerely and He never holds one accountable to that which was done in ignorance before knowing and committing to His path. So yes, indeed as you rightly said, when a person accepts Islam all his/her past sins are forgiven.
It was narrated that Abu Sa’eed Al-Khudri said:
“The Messenger of Allah (peace be upon him) said: ‘If a person accepts Islam, such that his Islam is good, Allah will decree reward for every good deed that he did before, and every bad deed that he did before will be erased. Then after that will come the reckoning; each good deed will be rewarded ten times up to seven hundred times. And each bad deed will be recorded as it is, unless Allah, the Mighty and Sublime, forgives it.’” [Sunan an-Nasa’i]
So, all of the person’s sins will be erases and his/her good deeds will be saved. And Allah Almighty multiplies the good deed to up to seven hundred times.
Allah’s Generosity
The generosity of Allah Almighty is limitless.
He provides countless opportunities for people to earn rewards and have their sins forgiven.
For example, narrated Abu Hurairah that the Messenger of Allah (peace be upon him) said:
“Allah, Blessed and Most High, has said – and His saying is the Truth: ‘When My slave considers doing something good then write it as one good for him. If he acts upon it then write ten of the same for him. And when he considers doing something evil, then do not write it. If he acts upon it, then write it. If he leaves it” – and perhaps he said: “if he does not act upon it, then write a good reward for him.’” Then he [the Prophet (ﷺ)] recited: Whoever comes with a good, then he shall have ten the like thereof (6:160). [Jami` at-Tirmidhi]
So, thinking about a good deed earns you a reward.
Doing a good deed earns you from 10 to 700 times its worth, whereas a bad deed is equal to only one bad deed, or it may be forgiven and replaced into a good deed if one sincerely seeks forgiveness from Allah.
Also, Abu Hurairah (may Allah be pleased with him) reported that Messenger of Allah (peace be upon him) said:
“The five (daily) Salat (prayers), and from one Jumu’ah prayer to the (next) Jumu’ah prayer, and from Ramadan to Ramadan are expiations for the (sins) committed in between (their intervals); provided the major sins are not committed.” [Muslim]
And reciting the book of Allah itself also earns one a wealth of rewards.
The Messenger of Allah (peace be upon him) said:
“Whoever recites a letter from the Book of Allah, he will be credited with a good deed, and a good deed gets a ten-fold reward. I do not say that Alif–Lam–Mim is one letter, but Alif is a letter, Lam is a letter and Mim is a letter.” [At- Tirmidhi].
This is just a glimpse of the Mercy and Generosity of Allah Almighty.
He opens His doors of forgiveness and rewards to anyone who seeks Him sincerely and He never holds one accountable to that which was done in ignorance before knowing and committing to His path.
Every single command that Allah Almighty asks us to do in this path is there to help us communicate and connect strongly with Him and purify our minds, hearts and souls and nourish ourselves spiritually, intellectually and physically.
He commands us to follow this path of Truth, peace, purity and growth and He helps us in it, rewards us for what is good, forgives our sins and shows us Patience and Mercy.
So, it is indeed such a noble and beautiful opportunity for the human being to seek Allah that way He asked us to seek Him because it is truly for our own success and benefit.
May Allah Almighty facilitate for all sincere seekers to find His path and live a truly satisfying and pure life that gives utmost peace and satisfaction to their hearts, minds and souls.
Ameen!
SOURCE: ABOUTISLAM
