kindly explain, eselam ....
The commentary of Ibn Kathir of Chapter 3, verse 85 [3:85]:
"And whoever seeks a religion other than Islam, it will never be accepted of him, and in the Hereafter he will be one of the losers."
Allah said next,
And whoever seeks a religion other than Islam, it will never be accepted of him....,
whoever seeks other than what Allah has legislated, it will not be accepted from him.
....and in the Hereafter he will be one of the losers.
As the Prophet said in an authentic Hadith,
Whoever commits an action that does not conform to our matter (religion) then it is rejected
According to Islamic teachings, any deed done for the sake and pleasure of someone other than Allah will have it rejected by Allah on the Day of Judgement. Moreover, the same applies to one who does a deed for the sake and pleasure of Allah and associates along side Allah someone else.
Hadith Qudsi*:
On the authority of Abu Hurayrah (may Allah be pleased with him), who said that the Messenger of Allah (peace and blessings of Allah be upon him) said:
"Allah (glorified and exalted be He) said: I am so self-sufficient that I am in no need of having an associate. Thus he who does an action for someone else's sake as well as Mine will have that action renounced by Me to him whom he associated with Me."
It was related by Muslim (also by Ibn Majah).
*Meaning of Hadith Qudsi:
Among the many definitions given by the early scholars to Sacred Hadith is that of as-Sayyid ash-Sharif al-Jurjani (died in 816 A.H.) in his lexicon At-Tarifat where he says: "A Sacred Hadith is, as to the meaning, from Allah the Almighty; as to the wording, it is from the messenger of Allah (peace and blessings of Allah be upon him)." It is that which Allah the Almighty has communicated to His Prophet through revelation or in dream, and he, peace be upon him, has communicated it in his own words.
In the verse it says that any religion other than Islam will not be accepted as a means of attaining Paradise because to live a life contrary to the commands of Allah means to disobey him and therefore one has no deeds which Allah will accept of him.