You have to first read and understand the three universal characteristics of all phenomenal existence - Anicca, Dukka and Anatta (Buddha's complete teaching is based on this discovery). Only then you will realize the reason why clinging creates re-birth. Since 'Anatta' means not-self ( there is no 'I' or 'me' in ultimate reality/ truth - the so called ‘I’ or ‘ you’ are a nothing more than a combination of five skandhas - or five aggregates), and it is because of clinging which created 'I' (me and my or mine) the ‘ego’, and the moment you let go of 'ego' you will realize that it is just an illusory world (called conventional world) created due to ignorance, this clinging- wanting pleasure and rejecting displeasure (duality) originate due to craving. 'Dukka' (un-satisfactory condition and suffering) arises because of 'Anicca' ( impermanence - ever-changing) and 'Anatta' not-self('ego', conditioning of craving ). It is the Mental formation with clinging (Sanskara - Upadana) that creates re-birth/Cause which acts as the force that pushes to the next existence. Therefore the mental formation without clinging to pleasure or displeasure which is called equanimity will not create re-birth, and this can be achieved only by observation and not getting involved to create cause (karma), the art of cultivating equanimity is to observe the five precepts and to practise Dana ( donate – giving without expecting anything in return, - let go process) , Seela - physical and mental discipline cultivating loving kindness ( Ethical and high moral values –have consideration for all living beings including environment ) and Bhavana – meditative practises to develop wholesome mental qualities. All these will finally lead to eightfold path.
In order to fully understand Dharma and to have faith in Dharma, you need to completely understand about the re-birth process as well as ‘Samsara’ or never ending process’/ cycle of existence. Since all existences are un-satisfactory, and bring suffering the only way to liberate from that is attaining Nibbhana. (energy cannot be destroyed however can stop generating energy)
Once you understand this, then you will need the effort and nothing but the effort to live according to Dharma. Knowing Dharma has no purpose if you cannot live according to Dharma. It’s like having a prescription for your illness with you but not taking the medicine that was prescribed due to many reasons.
Asking all these questions has no purpose without knowing the basics. It is like wanting to know the route to the moon without even having a rocket or become an astronaut.
The major part of Buddha Dharma is the path to purify your mind, since it is the mind that is the forerunner of all evil. Only in Buddha’s Teaching it says that the life existence is a combination of Mind and matter phenomena, where matter/ the Body consist of the five sense sphere. It is through these five sense sphere that everybody is trying to find pleasure and the sixth sense 'mind' that end up suffering more times than the matter. This happens because of ignorance and not understanding ‘Anicca’ and ‘Anatta’.