Many religious people say they know they are saved because they feel saved, or they have had some “better felt than told” experience. But I John 2:3 reads “And hereby we do know that we know him, if we keep his commandments.” So we don’t know we are saved based upon our feelings, but instead it is based upon whether or not we are obeying God’s new covenant law.
Remember the story in Genesis where Joseph’s brothers smeared blood on his garment so their father (Jacob) would think Joseph had been killed by a wild animal (Genesis 37:31-34)? It worked – Jacob mourned, just as if Joseph was dead. But the reader knows Joseph was still alive. Jacob’s feelings were based upon false information, and were therefore unreliable. So might our feelings be unreliable about our own salvation – if they are not based upon the truth of God’s word – only the truth will make us free from sin (John 8:32).
Revelation 22:14 makes it clear that our salvation is dependent upon our obedience to God’s word, as it reads “Blessed are they that do his commandments, that they may have right to the tree of life, and may enter in through the gates into the city” (referring to heaven). Our feelings are unreliable as they can be deceived. The only way to be sure of your salvation is to keep God’s commandments.
Back to I John 2, verses 4-5 read “He that saith, I know him, and keepeth not his commandments, is a liar, and the truth is not in him. But whoso keepeth his word, in him verily is the love of God perfected: hereby know we that we are in him.” So keeping God’s commandments is how our love for God is completed, and is how we know that we are in (fellowship with, a saved relationship with) him.