Which of you wishing to construct a tower
does not first sit down and calculate the cost
to see if there is enough for its completion?
It is important to avoid presumption in the spiritual life. If we simply assume we are sufficiently prepared and have all the necessary resources without confirming it in advance we may find ourselves in the embarrassing situation of laying a foundation and then coming up short. Another way to say this is that we are called to work out our salvation with fear and trembling, taking nothing for granted. The presumption that we already have enough has the unintended side effect of making us less ready to turn to Jesus for help. We need to renounce the things that give us confidence in ourselves because our confidence is not meant to be in ourselves, but rather in him, because, "God is the one who, for his good purpose, works in you both to desire and to work". A tower we build on our own will turn out no better than the Tower of Babel. But if we allow Jesus to use us as living stones in his temple we know that he himself will definitely complete the work.
If anyone comes to me without hating his father and mother,
wife and children, brothers and sisters,
and even his own life,
he cannot be my disciple.
Whoever does not carry his own cross and come after me
cannot be my disciple.
Even the best goods this world has to offer are not sufficient to bridge the gap between heaven and earth. It is true that we must honor our parents, love our children, and even love ourselves so that we are in a position to love others. But all of this will eventually crumble to dust unless it is unified into the one tower that can bridge heaven and earth, the cross of Christ. We read elsewhere that he is the true ladder that Joseph saw in his dream upon whom the angels ascended and descended (see John 1:51)
Or what king marching into battle would not first sit down
and decide whether with ten thousand troops
he can successfully oppose another king
advancing upon him with twenty thousand troops?
Jesus is the one with the strength and the spiritual forces to defeat the evil one and all of the principalities and powers of this present darkness. Without him, in our fallen condition, we simply aren't a match for the strength of the enemy. And in fact, without him we will be in some way complicit in systems of darkness and sin. So let us seek terms of peace with the army of the heavenly hosts. We know, after all, that it is they who win in the end.