There cannot be an afterlife because we are mammals and when we die we go to dust. Our spirits remain in the lives of others.
How do you know this? Where are you getting this from? My spirit was once somebody elses? Your spirit was another at one time? That's easier to believe than the fact that we are unique and created by a God who loves us?
If you're looking for me to "prove" heaven to you. I cannot. I absolutely believe in a heaven and a hell because of two things (the holy spirit and the Word of God) but I can't transfer that belief to you. Only the Holy Spirit can do this. Obviously the Holy Spirit has not. I can only point you in the right direction.
I can explain the afterlife to you tho.
I believe that we are put on earth to find, respond, and love God our creator. We have approximately 70 years to do so. Some more, some less. Some do, some never do.
When we die, our spirits go back to God for judgment. We will answer for what we did here on earth. Those that he Knew and had a relationship with here on earth are reunited with Him in heaven. Paul wrote that the believer is "absent from the body and present with the Lord" at death.
Those that he did not know and did not have a relationship with are placed in Hades awaiting future judgment. Their bodies are in the ground, but their spirits are in prison.
Death means separation. Physical death is a separation of the body from the spirit. Spiritual death is the separation of the spirit from God.
There are two births and two deaths. The first birth is physical. We are born into this world as babies. The second birth is spiritual. Our spiritual souls when we are first "born again" are infantile. That's where "born again" comes from.
We grow spiritually like we grow physically. We need nourishment to grow. If we don't get the right nourishment we are stunted in our growth and may even get sickly. At first we need milk and then solid foods. Our spiritual food is the Word of God which is what nourishes us to complete adulthood. It takes time to grow both physically and spiritually.
There's a saying that goes like this....."born once, die twice (physically and spiritually). Born twice, die once (only physically).
Adam and Eve when they ate the fruit that day, started the death process right then and there. Because they rebelled against God, they were to die twice which is physically and spiritually. But God in his goodness provided for them by sacrificing for them and their acceptance of this brought them back to him spiritually.
In the same way, God has provided us a way in the sacrificing of his son. We can either accept it or reject it. To reject it means to die spiritually one day. To accept his sacrifice on our behalf means eternal life to all those that believe. We will never die. It was the only way of provision for us since God will not allow sin into heaven.
Jesus came to show us the way out. That was the whole purpose to show us and make provision for our sin. All we have to do is belive and accept what he did for us. It's not hard. Even a child gets it.
Jesus said himself..."you must be born again." That's the only way into heaven. And only the Holy Spirit can do this. We can't will it, or make it happen. It's all from God.
I had nothing to do with my first birth (physical) and I had nothing to do with my second birth (spiritual). It was all God.