Yeshua says many things which may seem harsh, often in an arbitrary way. It’s difficult to understand Him in these contexts, so He is often misunderstood.
For example, when an enthusiastic young man decides to follow Christ, yet first wants to go home and say goodbye to his family (Lk 9:61), Christ replies, “No man, having put his hand to the plough, and looking back, is fit for the kingdom of God.” (62) Is Jesus telling him he can’t even tell his family about his life-changing decision, and bid them farewell as he starts off on his journey?
Looking carefully at His reply, Yeshua isn’t actually forbidding the disciple this last kindness to his family: He’s warning him about indecisiveness; his relatives will likely protest and discourage him, challenging the conventional wisdom of his decision and reminding him of his responsibilities to themselves and the larger community. “What?!! You’re going to abandon your family, leaving your little brother to handle everything all by himself? to follow who? Some rogue preacher you just met? And to do what? Where? You’re being impulsive, romanticizing about a revolution, but you’re going to get yourself killed! And maybe the rest of us too!” Family doesn’t generally take kindly to these sorts of decisions. (Mt 10:35-37)
Yeshua is indirectly prompting this dear man to look carefully into his own heart and count the cost; is this really what he wants? Is he willing to pay the price? to do what it takes to follow Messiah? Has he committed and focused his own spirit to take on the rigors demanded of the spiritual life? This isn’t a cake-walk; we’re called to take up our execution stake every single day. (Lk 9:23) Second-guessing will defeat us.
Those who start off in shallow passion and excitement after Messiah without doing this honest self-examination, this sobering kind of soul-searching evaluation, reflection and preparation (Lk 14:28), who have some ulterior motive, looking to advantage themselves — when the going gets tough, like the seed sprouting on stony ground, they’ll cool off, wither and fall away. (Mk 4:16-17) These are not fit for the kingdom of God.
This seems consistent with the rest of the immediate context; Christ responds to another enthusiast, willing to follow Him to the ends of the earth, that He Himself is homeless, having no place of His own to lie down at night. (Lk 9:57-58) Following Him means sleeping outside on the ground at times, in the rain and cold, going without food for days. (Mk 8:2-3) He’s suffering and calls us to endure hardness with Him (2Ti 2:3); are we in for that? (1Pe 4:1-2)
Those who aren’t willing to give up all to follow Christ (Lk 5:27-28), to forsake themselves for Him (Lk 14:25), to put Him first in every area of their lives, aren’t yet believing on Him, don’t yet know Him, and aren’t yet suited for the kingdom of God. (Lk 14:33)
The agricultural context of this metaphor is insightful; turning to look back while plowing a field will very likely result in crooked and uneven furrows, which are inefficient and wasteful.
Why would one do this? look back while plowing? Perhaps they hear someone calling to them, or a sudden unexpected noise. Or perhaps to check their work to see how straight their current furrow is. Even stopping in the middle of plowing a furrow can create issues. In any case, it reflects a lack of focus on and commitment to the task at hand.
When we take up a mission but don’t fully commit to completing it, allowing ourselves to be distracted and swayed such that we behave inconsistently, or lack wisdom in completing tasks, we invariably drift off course and create a mess. Evidently, this isn’t the kind of person who inherits the kingdom.
God sanctifies His children and disciplines them so they are fit for His kingdom.