Plausibly, entering into relationship with God and abandoning it later could be to God a great evil (analogous to divorce). This is relevant because such a great evil can be such that it would have been better for it to have never existed.1
God can know that starting the relationship (or starting it at time t) would cause the individual harm.1 (For example, precluding a better conversion time, or resulting in more crime-punishment) This is relevant because this would be a needless harm, and avoiding causing them needless harm is the kind of thing a loving and merciful God could plausibly choose to do.
• Daniel-Howard Snyder: “[If someone is just as likely to freely reject, be indifferent, or reciprocate] Then there is a grave risk in his coming to theistic belief. For if he comes to believe that God exists and then spurns His love, he is well on his way to reinforcing an extremely harmful disposition. In that case, the better part of wisdom may well be to let him form and/or confirm in himself a deeply entrenched disposition to love God.” [“The Argument from Divine Hiddenness” Canadian Journal of Philosophy 26:3 (1996): 448.]
• Laura Garcia: “Belief in God is normally more than a cognitive matter, and our volitional stance, (especially our attitudes) may be such that God may not give us more knowledge of Himself until we turn toward him with greater interest and oppenness.” [“St. John of the Cross and the Necessity of Divine Hiddenness,” in (eds) P. Moser & D. Howard-Snyder, Divine Hiddenness: New Essays (Cambridge, 2002), 86.]
Bringing some non-believers immediately into relationship could preclude a time of conversion for the believer which would yield better results (e.g. a proper longer/everlasting relationship rather than just a temporary one, or an everlastingly higher-quality relationship, or more).1, 2
• Travis Dumsday: “God must moderate His self-disclosure, delaying His personal revelations until we have some sense of our own fallenness and a measure of humility. And for those who do develop the necessary virtues such that they can handle open relationship with God, God will eventually grant such open relationship. In the meantime, uncertainty about ultimate questions brings home to us our own limitations, helping to build up the requisite virtue of humility and prompting us to seek diligently for the answers, which act of seeking, if persisted in, will itself build both humility and a greater love of truth.” [“Divine hiddenness and the one sheep” International Journal for the Philosophy of Religion (Forthcoming)]
• Travis Dumsday: “In the case of those who are personally responsible for their good disposition, he suggests that God might delay revealing Himself in order to allow the person to develop his/her character further such that the resulting relationship will be deeper and more genuine than it otherwise would have been, or to correct for defective motivation (i.e., the person might indeed be disposed to engage God in relationship, but for bad reasons, like wanting to secure power by devoting him/herself to this omnipotent being—here a similarity to Morris’ approach is apparent). For those who are well-disposed through no merit of their own (perhaps their good disposition is a product of upbringing independent of any autonomous reflection) God might wish to delay a personal revelation until the individual has autonomously appropriated that good disposition, on the ground that the resulting positive relationship will be more valuable inherently.” [“Divine hiddenness and the one sheep” International Journal for the Philosophy of Religion (Forthcoming)]
Bringing some non-believers immediately into relationship with God (marriage1) ones who will leave later, could result in these inviduals being punished more harshly for rejecting (divorcing) God and/or for their sins. This is relevant because being merciful is a property of God's, and mercifully preventing an individual from entering into the divine-human relationship they would not last in would be very merciful. It would save them from God's wrath.
To a lesser degree the same went for God's relationship to Israel. God frequently likens Israel and Judah to harlots, even going so far as to manifest this by commanding his prophet to marry a harlot.
• 2 Corinthians 11:2 -- For I am jealous for you with a godly jealousy; for I betrothed you to one husband, so that to Christ I might present you as a pure virgin.
• Hosea 1:2 -- The Lord said to Hosea, “Go, take to yourself a wife of harlotry and have children of harlotry; for the land commits flagrant harlotry, forsaking the Lord.” … Hosea 3:1 -- Then the Lord said to me, “Go again, love a woman who is loved by her husband, yet an adulteress, even as the Lord loves the sons of Israel, though they turn to other godsEntering into relationship and abandoning it appears to be worse than never having entered into relationship at all. (And yes, God knows that the sons of Abraham will return to relationship:
• Jeremiah 31:31-34 -- “Behold, days are coming,” declares the Lord, “when I will make a new covenant with the house of Israel and with the house of Judah, not like the covenant which I made with their fathers in the day I took them by the hand to bring them out of the land of Egypt, My covenant which they broke, although I was a husband to them,” declares the Lord. “But this is the covenant which I will make with the house of Israel after those days,” declares the Lord, “I will put My law within them and on their heart I will write it; and I will be their God, and they shall be My people. They will not teach again, each man his neighbor and each man his brother, saying, ‘Know the Lord,’ for they will all know Me, from the least of them to the greatest of them,” declares the Lord, “for I will forgive their iniquity, and their sin I will remember no more.”