What blocks the Christian possibility for modern people? At Least Two things...

One of the reasons that argument and persuasion (in general) are ineffective with modern people; is that their wrong ideas are based upon more-than-one false assumption. 

This means that if just one false assumption is challenged (and an argument can only do one thing at a time); the error remains - because held in place by the (currently unaddressed) false assumption. 

Modern Man begins with a conviction that death is annihilation - that death of the body (including brain, and all brain activity) entails total destruction of that person. 

Thus; rejection of the desirability of eternal resurrected life by following Jesus Christ, is held in place by the modern person's materialism; his unbelief in even the possibility of life after death; unbelief in a spirit (or soul) that can exist without the body and after the death of the body. 

To become a Christian, a person first needs to cease to be a "materialist". 

But, when a modern person is persuaded that there is more than "the material" the spirit is real, that there is a world of the spirit; then this is not sufficient to direct him towards becoming a Christian. 

Those who newly believe in a world of spirit are presented with - on the one hand - a Christianity that is manifest in the materialism of this-world, including the bureaucratic-institutional reality of the churches... 

And on the other hand, the newly 'spiritual' individual is culturally offered a variety of pure-spirit, 'oneness' ideals* - whereby the spirit is presented as a separate and superior realm of being, and the individual self (and our  thinking) as this-worldly incarnation-caused delusions that need to be overcome in order to enter fully the realm of spirit. 

Repelled by the bureaucratic materialism of Christian churches (each of which presents itself as essential in order to achieve salvation after death)...

The newly-spiritual person is told that he needs to leave behind his ego-self (and our thinking). 

Therefore; the idea of bodily resurrection after death becomes regarded not so much as nonsense; as actively undesirable - a 'clinging' to the delusion that is the body, and an egotistical refusal to give-up the autonomous thinking agent.   

This is important: After (and this is a difficult transition) a modern person becomes convinced that there is a spiritual realm; that the spiritual is eternal and therefore superior to the corruption and death of this world; and that he will survive bodily death in a spirit form... Then he is inclined to regard the Christian offer of bodily resurrection as a childish thing, a kind of simplistic regression, a step backwards not forwards.

The newly-spiritual person is likely to regard with disdain (or dismay) the Christian ideal of remaining a separate being from God - both physically separated by having a body, and mentally-separated by retaining selfhood and the capacity for independent thinking. 

While Christians regard love as existing between free-individuals; the newly-spiritual modern person is more likely to understand "love" as being universally-directed at the entirety of reality; and a state of complete absorption-into "the divine", which is also "everything".

For the newly spiritual modern person; 'spirituality' implies a giving-up of individuality, and a return to an original state of undifferentiated oneness. 

So, instead of the self being annihilated at death by ceasing to exist (as mainstream modern people believe); the self is annihilated after death by giving-up its selfhood and autonomy, and all capacity for thought - by assimilating-into-universality.      

My point is that the Christian finds himself at (at least!...) two removes from conversion of a mainstream modern materialist. 

One (big) step being to induce belief in the realm of spirit; but then there comes a whole other business of trying to explain what resurrection means, why Christians want it, what Heaven is like...

And why Christians desire to retain personal agency, the capacity for thought, and gain a "new body" after death. 

*Oneness spirituality may also appear in the guise of a quest for 'wholeness' or 'holism'; under the assumption that anything less than everything is incomplete, and thereby insufficient. Christianity is about eternally loving relationships, (and with each loving relationship unique, irreplaceable) - not about attaining oneness/ universality/ wholeness/ holism.