Christianity proclaims that its founder Jesus Christ is Himself God in human flesh, not a way or a path to God. Further to this it claims that its founder is not dead but is alive forevermore. It also proclaims that Jesus Christ is the core and center of true religion, not human works or achievements, no matter how pious. Thus it teaches that we cannot work our way to God, but that God has, in Jesus Christ, come down to us and done everything necessary to bring us back to God. This also runs contrary to some aspects of some of the other religions which teach that with the 'god within' we can attain to holiness or perfection or however it is described. Christianity teaches that although there is such a thing as 'the light which lightens every man' (person) it is not the same as us being able to reach God by our own efforts or save ourselves.
This is also possibly the most offensive difference in that people do not like to hear that they cannot do it themselves. They also like to think they are not so bad and so can reach God, however they conceive Him by self-improvement. Sometimes they also may refer to what the Bible calls sin as mere 'character faults' which they can simply improve on by their own efforts and reform themselves. The Bible proclaims clearly that this is impossible without being born again to faith in Jesus Christ. What it says is that what is dead cannot perform the actions of life, although we can of course sense our need for God.
Judaism is probably the closest of all of the religions to Christianity with a common heritage. Christians regard the Jews as a blessed people as God's chosen ones, although they differ essentially in two main areas. The first is the identity of Jesus Christ as the Messiah and the second the ongoing place of the Torah or Law in terms of pleasing God.