How? well first the new testament says that we are a soul we don't have a soul also there is nowhere in it where it says we have an immortal soul. It says that all people, die and lay in the ground until judgement day when then they will be risen from the ground. Evidence from near death experiences, out of body experiences and many other areas of evidence make this idea false.
Also mainstream science has the view that mind equals brain function so here christians and mainstream scientists agree that we cease to exist when we die. Is it true? or is there an alternative not just an alternative but one that fits the evidence that has been gathered for over 100 years yes there is it is from reliable evidence such as the cross correspondences, reincarnation evidence, the newspaper and book tests. This evidence points strongly to the view that we have an immortal soul but not just humans but all species are likely to transition over to the afterlife realms where conditions are much better.
I have talk a lot i know about the evidence for the survival hypothesis but i believe it needs to be stress that it has significant role in the foundation of all living things on this planet. The implications are enormous.
I like to leave this post with a quote from Professor Sir William Barett
"I am absolutely convinced of the fact that those who once lived on earth can and do communicate with us. It is hardly possible to convey to the inexperienced an adequate idea of the strength and cumulative force of the evidence." William Barrett