Brother i think you miss understand the concept of faith. Faith is the belief in something, it is not the knowledge of something. Those are 2 entirely different things. When u have faith in something, its natural to sometimes feel doubt in your heart about it due to fluctuations of emotional factors that can conflict and interact with your belief. There is even a hadeeth that states that, a persons belief fluctuates naturally from time to time, sometimes increasing sometimes decreasing, this is why u should always practice prayer and supplication to your lord to maintain a strong faith.
However, i feel like what u seek is more than that. You seek affirmation of your belief, you seek knowledge ... and this unfortunately is almost unattainable so long as you are still living in this world. Meaning that the only way you can attain knowledge of the beyond is through death. This knowledge that you seek is often known as "Yakeen" in arabic (
الْيَقِينُ)
. Even when God mentions a command to the Prophet regarding death, He refers to it as Yakeen
وَاعْبُدْ رَبَّكَ حَتَّىٰ يَأْتِيَكَ الْيَقِينُ
And worship your Lord until there comes to you the certainty (death). [Quran 15:99]
This is the entire concept and reason of this life, is to test our faith, not knowledge. So its ok not to have this certainty with you because your not suppose to ... your suppose to have strong faith!
The closest thing you can get to having certainty in your belief is to actually go out there and test it. Test islam and see how well it fairs with other faiths, see how it holds up on its own and give it a FAIR chance. See its miracles, concepts, rules, ...see the reasons behind these rules. Promise the Creator that you will submit to his faith if He shows you his path and give him reason to believe you, and i promise you he wont turn you down. But i strongly urge you to go out there and do your own research more than twice until your contempt with it and open your heart to the chance that there might be your creator waiting for you to stretch out your arms to him on the other side. Do that alone until your heart is contempt with the result and i promise you, you wont need anything more than that. Dont be discourages if hardship befalls you or you start feeling resistance, because its more than natural to find obstacles that tries to stop you from doing whats right (As it usually is in this world. Its more easy to do the wrong than the right) Its actually a sign that you are probably doing what u would do.
I pray to Allah that he guides you to his path and to what is best for you in this world and the hereafter. Salam
