There is a difference between following a religion and following God.One can follow all the rules and traditions of their religion and never have a heart for God.
God says "On that day many multitudes will say to Me 'Lord, Lord, did we not prophesy in your name and in your name drive out demons and in your name perform many miracles?' "And then I will declare to them, 'I never knew you. Away from me, you evildoers!:
What is God saying here? Notice first That the people call him "Lord Lord". This is letting us know that the people truly believe God to be Almighty God. They believe that they have been following God. They believe they have done all the right things, known all the right things, And said all the right things. In their hearts and minds they believe they should be welcomed into paradise. They have followed all the rules, and yet God does not welcome them into paradise, and tells them to leave.
You see folks it's not enough for us to follow the rules and traditions of our religion whatever that religion may be. Most of the rules and traditions of any religion have been instituted by man, They are some mans interpretation and understanding of what God is saying in Scripture. And because man does not understand God's ways without going to God himself, they are full of logical yet wrong understanding and ways.
God tells us to "test the Words to see if they are of God" or not. Each of us is responsible for going to God and checking to see if everything we have ever been told and believe, is Truth from God or merely some man's understanding. It's a proven psychological fact that if someone is told a lie often enough they will believe that line to be true. And nowhere are more lies told, though truly believed to be true, then in religion. People are repeating what they have heard and believed to be true, yet they are guilty of never going to God and asking him if it's truly his Truth or not. So although they sincerely believe it to be true, It is in fact a distortion of God's truth.
And of course everyone thinks that "MY" religion is right and everybody else's religion is wrong.The truth is, If there is an argument or a conflict between two religious beliefs, it is not a case of one being right and one being wrong, but rather both are at least partly wrong. It is impossible for us as humans to choose what is right and what is wrong with all the different theories put out by man. There are literally thousands of religions and denominations and sects. Without God's help, there is no way we could ever hope to choose which one is right and which one is wrong. The only way to know what God's truth is is to be seeking him and his truth. To be asking God what his truth really is, with an open heart and mind that is willing to accept that everything we have ever been told might be wrong. If we refuse to believe that what we think is wrong we won't ever hear God's truth from HIM.
This is why God warns us that on the day of judgment, many multitudes will think they have done all the right things and will enter heaven, when in fact they haven't. Yes they have followed what they believe to be true, but they never truly got to know God. Without knowing God for who he really is we cannot love him, we can only love an illusion,An idea of who we think God is. We cannot do the will of God, if we don't know what it is. We cannot follow God and Be like him, if we don't know him.
Eternity is far too big to be left to chance, or the opinions and ideas of others. Go to God, get to know him, learned his Truth from him. Then, on that day, you will hear "well done you good and faithful servant" rather then "depart from me".