Why does John 3:16 say that whosoever believeth on Him (Jesus) should not perish but have everlasting life, while John 5:24 says he who…believes in Him (God the Father) who sent Me (Jesus) has everlasting life? Do you need to believe in Jesus or believe in God the Father for everlasting life?
It is not just John 3:16 that tells that it takes faith in Jesus in order to gain everlasting life. Over a hundred times in the NT, we see that same truth.
Even John 5:24 tells us that we must believe in Jesus to have everlasting life!
In John 5:24 to “hear My words” means to believe Jesus’ message of everlasting life. Thus, the coordinate phrase “and believes on Him who sent Me” is another way of saying the same thing. One cannot believe in God the Father unless he believes in the Lord Jesus Christ whom He sent.
Later, Jesus repeated this claim, saying, “He who believes in Me, believes not in Me but in Him who sent Me” (John 12:44).
He also said, “the Father who sent Me gave Me a command, what I should say and what I should speak. And I know that His command is everlasting life. Therefore, whatever I speak, just as the Father has told Me, so I speak” (John 12:49-50).
The Jews of Jesus’ day for the most part rejected Jesus (John 1:11). However, nearly all those same Jews claimed to believe in God. Like many in Christendom today, many Jews of the first century thought that they would spend eternity in the kingdom if they believed in God and persevered in faith and good works (John 5:39-40).
The point the Lord Jesus is making in John 5:24 is that to believe in God the Father one has to believe in Jesus whom He sent.
Jen Psaki is President Biden’s Press Secretary. He sends her out each day to communicate his message. One cannot believe the message of President Biden without also believing the message that he sent Jen Psaki to deliver.
Admittedly, that illustration is not infallible. Press secretaries sometimes say things that are contrary to the wishes of the President. However, since Jesus always gives the precise message that the Father sent Him to give, we can take it to the bank that the only way to believe in God the Father regarding His saving message is to believe in His Son, the Lord Jesus Christ.
People today are disposed to reject the free gift of everlasting life as silly, too easy, too cheap, and illogical. So, they either define faith as including turning from sins, surrender, and commitment to obey, or they say that it takes faith plus perseverance in good works to gain what they call final salvation. But the reality is different. Jesus Himself said that whoever believes in Him and His promise of the free gift of everlasting life is finally saved from that point onward. God the Father sent Jesus with this message. If we replace Jesus’ message with a message that we like more, we are rejecting not only Jesus, but also God the Father.