In these passages we are told, “He who believes in the Son has Eternal Life; but he who does not obey the Son shall not see life, but the wrath of God abides on him.” Eternal Life is given to those who believe in Jesus. It is contingent on a continued and active belief in Jesus. That belief is evidenced by obeying Jesus.
The Bible says that Jesus is the Word of God. Evidence of our belief is our obedience to what the Word of God or the Bible tells us to do.
The Bible also says, “He who does not obey the Son shall not see life.” Therefore, Eternal Life as defined by the Bible can be both gained and lost while we are alive.
By our choices we can either keep Eternal Life or lose it. If we do not have an active belief in Jesus, we do not have Eternal Life. If we do not have Eternal Life when we die, we are at risk for not being allowed into Heaven.