My attempt to answer a friend's question…

"Hey Friend... suggestions for a sermon for pulpit supply in a Presbyterian church... this may be one week or a few..... they have an interim pastor coming the end of October..."

Sermon suggestions?  Do you mean such as what text, or what topic?  I'm assuming that is what you are after, so here goes.

For the most part I believe that the text preached drives the sermon, so for me the big question is deciding the text.  As I study it, and pray, (and it's always best to proceed in the opposite order, i.e. prayer first!) then I take the sermon in the direction I believe God is leading it to lead through the text.  I did a "series" (I have a bit of a distaste for  the 'series' concept) last year where I had a topic first, or rather a question, and then found and explained pieces of scripture that answered the question.

So you are preaching once, and possibly a bit more, for the same congregation, but what to preach?  Using the Revised Common Lectionary (RCL) is one option.  If the Presbyterians you are preaching to are of the PCUSA persuasion this may be where their sermons frequently come from.  When I began I used the RCL for nearly a year as the primary place to select my texts from. 

Each week the RCL has readings from the OT, Psalms, Gospel and somewhere else in the NT.  Prayerfully consider the readings and see if one of them seems to be the thing to bring to the particular congregation.  Sometimes two readings can fit well together.  I have some issues with the RCL, but since you are preaching just once, or maybe a few Sunday's for one group, that is a conversation for another day. 

It may be that you are personally using a devotional book or following a Bible reading plan.  In that case there may be a text in your reading that strikes you as something to explore and develop more fully as a sermon.

If you are preaching someplace that is glued to the liturgical calendar then it may be that your sermon is developed in conjunction with an event on the calendar.  In that case the RCL should be the source of your text.  On the other hand today I preached from Mark 1:1-11, where Jesus rides into Jerusalem.  Traditionally it is a Palm Sunday text but I am preaching my way through the Gospel of Mark, leaving Mark for only rare occasions, such as Advent, Christmas, Palm Sunday and Easter.  I rarely get feedback on my preaching but on the way out today one man told me that the message was just what he needed to hear, so I was glad to have stayed with that text today, despite its traditional placement. 

If you are preaching one week, and maybe a few more, you could also do a "series"  around a character of the Bible, such as Moses or Peter, taking snapshots of a few periods of the person's life.  If you did that I would take a NT character, rather than preaching several times in a row from the OT to a congregation that isn’t your own flock. 

Whatever you do you have to, in some way, get the Good News of Jesus in front of the congregation.  In every sermon, whatever your text, without exception, in some way, Christ has to be lifted up and shown to make a difference.  This is much easier said than done. 

Another way of looking at this is that the Christian church is not some kind of social club.  It is not one of many different but equally valuable organizations.  Jesus is the way and the truth and the life.  Or as Paul wrote to the church at Corinth:

"For the word of the cross is folly to those who are perishing, but to us who are being saved it is the power of God."

People who already embrace the Good News have to be comforted, encouraged, reminded and strengthened as they hear it again. 

And those who are presently on the outside need to see that everyone, without exception, is a sinner in the presence of God.  They need to see that there is no other hope for sinners  outside of Jesus.  And lastly, that there is no one who is too far gone to be beyond the saving touch of Jesus.

Some people may say that people who have an evangelical approach to the Gospel place too great of an emphasis on the cross.  I say that if you are going to stand in the pulpit and not bring the core of the Gospel then you might as well be talking to a Rotary club, or the Jaycees, or what have you. 

Hope this is helpful.  Any more questions? Ask away!  And in your preparation and preaching may all the glory be to God!

Addendum: The picture is Charles Spurgeon, the Prince of Preachers.  Spurgeon felt that perhaps the hardest part of preaching was choosing a text, something he worked on throughout the week.  He began his actual sermon preparation at 6 PM on Saturday evening, staying at the task until he felt he had sufficiently prepared for Sunday morning.  This method should only be used by the most gifted of preachers!

Scripture quotations are from The Holy Bible, English Standard Version® (ESV®), copyright © 2001 by Crossway, a publishing ministry of Good News Publishers. Used by permission. All rights reserved.