The phrase "unavoidable part" refers to something that is necessary or bound to happen. It implies that there is no way to prevent or avoid this particular aspect or aspect. Full definition
While stress is a normal, unavoidable part of life, it needs to be managed in appropriate ways if we plan to stay lean and healthy. (turbulencetrainingforabs.com)
And perhaps such feelings are a necessary and unavoidable part of growing up, of making that important distinction between oneself and one's parents. (rachelheldevans.com)
It simply means suffering as unavoidable part of life has its special place in process of redemption and Christ calls us to be patient when suffering hits. (redeeminggod.com)