Both Christians and Muslims seem to largely labor under a range of false pretenses and assumptions that developed in Christianity by the time Islam was invented, about what salvation means and is from. Islamic apologists correctly attack Christian theological claims that a) Christ promised to return and judge in his own generation and b) he is yet to keep that promise, and in fact he can’t, since we are now 50 generations later! But supposedly, he will.
Muslims deserve to know what Christians should know but generally don’t: the whole heaven and hell construct is a misunderstanding and a foreign concept. Christ never taught that there are two eternal destinies for individuals and the goal of ‘salvation’ is to avoid hell and attain heaven (at least in the personal post-mortem experience sense). Salvation, in the original Christian teaching, was from the slavery to sin, and from the broken and corrupt ways of living and treating each other.
Christ kept his promise and came in judgement and destroyed the Israelite system and kingdom that killed him and persecuted his followers, as he destroyed its house built on the sand with the flood of men of lawlessness and war.
And he kept his promise to build his church, his body, the immortal resurrection body, his kingdom, that brings healing and life to the world, freeing men from slavery to sin and enthroning men to rule over the beasts rather than each other.
Muslims in particular have suffered under Islam’s legal, social and political failures to deliver peace, healing and wholeness, and has enthroned the beasts to rule over men, as men rule over each other and impose their version of the knowledge of good and evil.
Christians have done better in creating and building social, legal and political institutions that restrain the beasts and keep them down, and defanged, notwithstanding the erosion of the original pacifist institutions of gentleness and restraint.
If Christians can rediscover and restore its original and authentic theory and practice – which on various matters it often has – and back away from unhelpful corruptions and innovations, it can offer Muslims a more attractive and more different approach, as well as addressing some of the valid objections against misguided Christian eschatology.