Assurance. Every Christian wants it and needs it but not every Christian has a lot of it. The burning question is: how do I get it? The answer to that question is too complex for one post here. Yet there is something about Christian assurance that I found come up in my Bible reading program.
Recently my Bible reading program had me in Luke 6. There Jesus gives his statement about the house built on solid foundation and the house built on no foundation at all (Luke 6:46-49). This comes at the end of Luke's abbreviated Sermon on the Mount (the fuller version being found in Matt 5-7). It contains some ethical nuggets in Jesus' teachings displaying the life of a redeemed kingdom citizen.
Jesus' words in Luke 6:46-49 serve as a fitting close for the section as he presents the one who "hears his words and does them" as one who built his house on a solid foundation. The one who neither hears nor does what Jesus says (cf. Matt 13:13-15) is as one who built a house with no foundation. When a harsh stream comes, the first house stays put while the second is destroyed in a great destruction.
Now, I've read and heard this parable many times before but only recently did I ask the question "why did Jesus use this imagery to describe these kinds of people?". In other words, he already established well the difference between the two in the verses prior when he discussed the distinction between a fruit bearing tree and a non-fruit bearing tree (Matt 6:43-45). There the distinction is made in terms of fruit bearing. But here in this text there seems to be more than just a distinction being made but a statement about what happens to these two kinds of people when trouble comes. The trouble being the harsh stream. This is where assurance comes in.
Where the house built on the foundation (the hearing and doing person) endured the weather, the house with no foundation (the not hearing and not doing person) was destroyed. One meaning to draw from this is in terms of an ultimate eschatological destruction of judgement. Those who proved by their obedience to be truly born-again believers will be spared (spared on the basis of the righteous blood of Christ with the evidence being the obedience). Those who prove to be unregenerate by their deeds are cast into eternal torment. Still, I don't think that's the only thing going on.
The wave can just as well be read as something that causes a potential blow to one's assurance whatever that might be. This certainly would be in line with the Bible's usage of water imagery to describe chaotic and evil realities (Ps 65:5-7, 108:28-29, Isa 43:16-17, cf. Rev 21:1). The person who labored in spirit-wrought obedience has evidence to point to displaying that they truly are born again thus having all the more protection from a potential blow to their assurance. They can see that God has worked in them and reason that they truly are Christians. This is precisely what John is getting at in 1 John 2:5-6, "whoever keeps his word, in him truly the love of God is perfected. By this we may know that we are in him: whoever says he abides in him ought to walk in the same way in which he walked."
WCF 18.2 calls these "inward evidences of grace". The personal and subjective proofs that we are truly Christians. Where assurance first and foremost rests on God's own promises of salvation in Christ (as WCF 18.2 says), these inward evidences are also necessary. As Paul put it in Rom 8:16, "The Spirit himself bears witness with our spirit that we are children of God"