A Muslim is advised to repent to Almighty Allah on daily basis and to sincerely ask for His mercy and forgiveness. Islam warns Muslims of committing horrible and grave sins and warns those who do them of a severe punishment in the Hereafter. Therefore, if anyone has done any such sins, he has to regret his act and sincerely repent to Almighty Allah before it is too late.
On the other hand, it should be clear that judging people of either going to Paradise or Hellfire is in the hands of Allah alone Who is Just in His Judgment and the Most Merciful to His servants.
Dr. Sano Koutoub Moustapha, deputy chairman of the International Fiqh Academy and professor of fiqh and its principles at the International Islamic University, Malaysia, states, Indeed, Islam calls upon Muslims to repent to Almighty Allah no less than 100 times per day as the Prophet (peace and blessings be upon him) used to do. Islam also reminds Muslims that as Allah is All-Forgiving while at the same time, He punishes those who go against His orders and injunctions. Surely, Jannah is only meant for those who are clean or have been cleared from all their sins. For those who commit sins and neglect repenting or seeking the forgiveness of Almighty Allah, they will face the punishment for whatever they did. Their duration in Hellfire, is in the hands of the Almighty. It is up to Him to forgive them and allow them to enter Jannah later.
Accordingly, we must bear in mind that there is no guarantee at all that all Muslims will eventually enter Jannah. Only Almighty Allah knows that and only He will decide. In this context, one must distance him or herself from those sins which Almighty Allah promises that those who commit them will be in Hellfire forever such as killing a Muslim or any innocent human being. I do not accept the interpretation of the word ‘forever’ in the verse meaning a long period of time. This is in the hands of the Almighty who alone knows the duration of punishment of those who commit grave and horrible sins if they pass away without repenting and regretting.
Certainly Hellfire is not a place one would choose to go even for just few moments! Therefore, we should refrain from anything that might lead us to that horrible destination.