Jesus made it clear that many who claim to be His disciples are actually false disciples.
21 “Not everyone who says to Me, ‘Lord, Lord’, shall enter the kingdom of heaven, but he who does the will of My Father in heaven. 22 Many will say to Me in that day, ‘Lord, Lord, have we not prophesied in Your name, cast out demons in Your name, and done many wonders in Your name?’ 23 “And then I will declare to them, ‘I never knew you; depart from Me, you who practice lawlessness!” Matthew 7:21-23.
How does one know and do the will of God? When the Jews asked Jesus what they needed to do in order to do the works of God, Jesus answered them and then described the work the Father had given Him to do.
29 Jesus answered and said to them, “This is the work of God that you believe in Him whom He sent.”…. 35 And Jesus said to them, “I am the bread of life. He who comes to me shall never hunger, and he who believes in Me shall never thirst. 36 But I said to you that you have seen Me and yet do not believe. 37 All that the Father gives Me will come to Me, and the one who comes to Me I will by no means cast out. 38 For I have come down from heaven not to do My own will, but the will of Him who sent Me. 39 This is the will of the Father who sent Me, that of all He has given Me I should lose nothing, but should raise it up at the last day. 40 And this is the will of Him who sent Me, that everyone who sees the Son and believes in Him may have everlasting life; and I will raise him up at the last day.” John 6:29, 35-40.
Doing the will of God entails seeing Jesus Christ as He is revealed in the Scriptures, the Bible, and believing in Him. The will of the Father and of Jesus is to save lost sinners, forgive their sins and give them eternal life as they repent of their sins and believe in Him. Those who believe in Jesus Christ will believe and obey the Bible, which is equal to doing the will of the Father in heaven. Those who reject the Bible as the Word of God give evidence that they are lost and bound for hell.