Atheism is an active assertion which must either be made through faith or by facts which may be tested.Agnosticism requires no such rigour.
Atheists must be challenged as to which position they adhere to.
Christians might respond with Psalm 34:8 - "Taste and see that the Lord is good."
The Christian position may be tested on an individual basis.
A 'step of faith' is required and God will honour that - if done honestly and with an open heart.
[Thanks to Randall Hardy for directing my thoughts in this direction.]
