He that hath the Son hath life… – 1 John 5:12

Faith in Jesus is good evidence of life, because of the things, which accompany it. Now, no man ever did come to Jesus Christ and receive Him until he had felt his need of a Saviour: no sickness, no physician: no wound, no surgeon. No soul asks for pardon or obtains it till he has felt that sin is an evil for which pardon is necessary; that is to say, repentance always comes with faith. There must be a loathing of sin and a dread of its consequences, or there is no faith. Now, as repentance is an evident sign of life, faith in Jesus must involve spiritual life. What if I say that repentance is like the cry of the new-born babe, which indicates that the child is alive? That cry of “God be merciful to me a sinner!” is as sure a sign of life as the song of cherubim before the throne. There could have been no laying hold of Christ without true repentance of sin, which repentance becomes in its turn a clear proof of the possession of the inner life which springs from incorruptible seed, and therefore liveth and abideth for ever.

No soul believes in Jesus Christ without exercising its faith and its desires in prayer; but prayer is the breath of the soul, and where there is breath there must be life. Can the dead pray unto God? Shall a dead soul cry out for mercy? …He that hath an interest in the Lord Jesus, since his faith is attended by repentance and prayer, and many other holy graces, has a multitude of sure and certain evidences of eternal life within the soul. ~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/0755.cfm