'Predestination v.s. Free Will' is a perennial debate. What follows is a perspective that I have developed concerning the issue.
First of all, the theological discussion on this topic is not primarily concern over objective truth per se, but subjective sensibility. Those who insist on the truthfulness of one position is in essence asserting one's subjective inclination for senses (i. e. meaningfulness) over the disagreeing party. To get what this means, one has to understand the rationale in both schools of thought.
Predestination-ism:Understanding the rationale underneath both systems of thought reveals that the predestinationists and free-willists affirm what they affirm due to the very same reason: that is to secure the human's capacity to arrive at and appreciate meaning. In other words, to be sensible.
Those who are for predestination assumes that our appreciation for meaning of anything can only be derived from God's sovereignty. Therefore (a) the Creator's sovereignty is absolute and necessary, while (b) the creation's/creatures' are contingent or necessarily not necessary. Hence in order for us to make sense of anything (for e.g. our salvation), we have to affirm both (a) and (b).
Unless we affirm both, we (the subjects) cannot construe and possess any meaning in anything (can't fully be assured of our salvation). And by 'anything', that includes our (subjective) appreciation of human's consciousness and decision. Hence, if the Creator's sovereignty is compromised, predestinationists believe that we have lost the ground to affirm our capacity to arrive at meaning; placing us in the position of not able to know or understand anything at all.
Those who are for free-will assumes that our appreciation for meaning of anything can only be derived from human's consciousness and decision. Therefore (a1) human's consciousness and decision are absolute and necessary, while (b1) God's is contingent. Hence in order for us to make sense of anything, we have to affirm both (a1) and (b1).
Unless we affirm both, we (the subjects) cannot construe and possess any meaning in anything. And by 'anything', that includes our (subjective) appreciation of God's sovereignty. Hence, if human's consciousness and decision are compromised, free-willists believe that we have lost the ground to affirm our capacity to arrive at meaning; placing us in the position of not able to know or understand anything at all.
Therefore it is the subjective sensibility that grounds and motivates both groups to affirm what they affirm rather than their possession of objective truth for their conclusion (which they often claim to be the case).
Besides both groups' relentless desire to protect human's capacity to appreciate meaning, both sides also share the following three affirmations:
1) Ontological distinction between God and us. (God/human freedom, God/human sovereignty, God/human knowledge, God/human wisdom, God/human capacity).For these reasons, neither sides of the debate are warranted to assert certainty of their own theological preference over against the other, be it predestination-ism or free-will-ism.
2) Temporal distinction between God and us. (God/human relation to time).
3) There are passages in the scriptures that can be contextually and validly argued in favor of both groups. (If anyone is doubtful of this, consult some of the best literature from both camps in the market. For examples, D. A. Carson, Simon Gathercole, G. K. Beale, and John Piper on the predestinationist side, while Joel Green, James D. G. Dunn, and Ben Witherington III on the free-willist side).
This, I see as an approach that acknowledges both groups' theological integrity that promotes unity and mutual understanding without violating or dismissing each other's concern and tradition. Through this framework, a predestinationist can whole-heartedly affirms the theological integrity of a free-willist, and likewise the latter can unhesitatingly acknowledges the former's.