Even when we sincerely follow spiritual path with full devotion and faith yet why should we face adversity in life?
Following spiritual path is not a blanket ticket for smooth sailing in life. It's not an assurance from God that no untoward incident will take place in life. Whatever situation arises in life, arises because of our own Karma (past actions) and we may have to suffer the result of these karmas. The difference between an ordinary person and spiritually evolved person is not in not having adverse or unfavorable situations in life but in how one reacts to these situations. Situations in life may or may not change by following spiritual path but our situational reactions certainly changes. One evolves to an equilibrium state and reacts positively even in an adverse situation. One definitely becomes stronger in dealing with unfavorable situations.
Adversity in life has been faced even by Gods such as Rama, the Buddha, Jesus Christ and highly evolved saints such as Ramakrishna Paramhamsa, Ramana Maharshi etc.