Here is the tree that brings forth good fruit because it is a good tree, a tree that has been made good by the Lord. The root cause of our obtaining eternal life remains always the gift of life through Jesus Christ, and his atoning death for those who believe.
What is the ‘well-doing’? It's not earning God's favour. You cannot do that. You say, ‘I need eternal life.’ Like Christian in Bunyan’s Pilgrim's Progress, suddenly it is put into your heart, ‘I must get to the celestial city. I must have heaven. I must have God. I must know that I am on the road to heaven. Oh, to have everlasting glory when I will have purity and character and understanding of all things and perfect communion with God and my Saviour in the everlasting bliss.’ The whole aim, the whole object of the exercise is the end of the journey and heaven; you cannot live the Christian life without that aspiration constantly in front of you. This is a tremendous thing.
There is a lot of nominal Christianity about, even in Bible-believing churches these days. If somebody comes to church and says, ‘I like this message of Christ; I like this message of the gospel. I am going to repent of my sin, and I am going to ask for salvation so that I am going to go to heaven.’ If they do so, but not very deeply or genuinely, and they are not really converted, then they are not covered by this verse. They are not people ‘who by patient continuance in well doing seek’ for God’s blessing and eternity. They think they believe the gospel; they have made their profession of faith, but they do just the same things more or less with a little bit of improvement on what they did before. Their priorities are for fun and enjoyment in this world, fulfilling their ambitions, having a great time. When you see genuine believers, you look at them and you say, ‘That person continues to follow the Lord, and trust in Christ, and do his bidding. That person would never claim to be highly righteous, but they are genuine and sincere, and they are kind, and they are striving, and it is heaven that they want, not things on earth.’ So righteousness is necessary. A shallow belief is no good. There must be a level of trust in Christ and a giving of yourself to him that makes you a different person. God changes you.