The biggest and ultimate question is the question Jesus asked His disciples: “Who do you say that I am?”
Then Jesus and His disciples went out to the villages of Caesarea Philippi; and on the way He asked His disciples, “Who do people say that I am?” They answered Him, “John the Baptist; and others say Elijah; but others, one of the prophets.” And He asked them, “But who do you say that I am?” Peter replied to Him, “You in contrast to the others are the Christ (the Messiah, the Anointed).”
Mark 8:27-29
That You May Know
The Apostle John writes in his first epistle, “And this is the testimony: God has given us eternal life. And this life is in His Son. Whoever has the Son has life, and whoever does not have the Son of God does not have life. I write these things to you who believe in the name of the Son of God that you may know that you have eternal life.” (1 John 5:11-13) Jesus Himself said: “Whoever believes in the Son has eternal life; whoever does not obey the Son shall not see life, but the wrath of God remains on him.” (John 3:36)
Obey The Son
Truly believing in the Son includes having the disposition to obey the Son. Those who claim Jesus as Savior also submit to Him as Lord, according to His will. As Jesus said in His Great Commisssion: “All authority in heaven and on earth has been given to Me. Go make disciples . . . baptizing . . . teaching them to obey everything I have commanded you.” (Matthew 28:18-20) This necessitates a belief in all God tells us in His Word, the Bible. Jesus consistently affirms concerning all the Scriptures, “Thy Word is truth.” (John 8:31) “Scripture cannot be broken.” (John 10:35) “If you abide in My Word, then are you My disciples indeed, and you shall know the truth. ” (John 8:31)
So Jesus was saying to the Jews who had believed Him, “If you abide in My word continually obeying My teachings and living in accordance with them, then you are truly My disciples. And you will know the truth regarding salvation, and the truth will set you free from the penalty of sin.”
John 8:31-32

Partial Obedience is Disobedience
Jesus doesn’t give us the option to pick and choose what to believe and when to be obedient. Partial obedience is disobedience. With Luther I confess: “I believe that Jesus Christ, true God, begotten of the Father from eternity, and true Man, born of the Virgin Mary, is my Lord.” Who do you say He is?