After ten years in the role, Clifford told Premier he felt God was calling him to something else.
He said: "For my wife and I, over the last few months, we've sensed that change was in the air for us personally, but also for the organisation itself.
"Through a combination of prayer, some prophetic insights that people have given us, we just felt it was the right time to be making a change and to be moving on to something fresh, and for the organisation to find someone else to follow in my footsteps."
During his time in the role, Clifford has overseen growth in the Evangelical Alliance including expanding its work within black and minority ethnic communities.
He's also seen the launch of the Great Commission website equipping Christians for evangelism in the UK.
Paying tribute, Dr Tani Omideyi, chair of the Evangelical Alliance board and senior pastor of Temple of Praise, Liverpool, said: "A proof of the changes Steve has brought about over his 10 years as general director is seen in the fact that the Evangelical Alliance looks and sounds different today than when he took over its leadership role.
"His outstanding achievement in deepening unity across church traditions and racial backgrounds provides a sure foundation on which hopefully future evangelicals will build. It has been my joy and privilege to support him during some of this period."
The Evangelical Alliance says it will shortly begin the search for Steve's successor.
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