3:6 God gave the increase. The soul-winner should rejoice when someone accepts Christ, but not boast, for it is God the Holy Spirit who has actually saved him. Those who sow, or water, or reap may have a part, but the praise belongs only to God.

3:7 planteth. Although men are privileged to sow the gospel seed, it still remains the work of God, for “the seed is the word of God” (Luke 8:11). Similarly, men may water the ground, but the water also is the word of God, “For as the rain cometh down, and the snow from heaven,…So shall my word be that goeth out of my mouth: it shall not return unto me void” (Isaiah 55:10-11).

3:8 are one. When God gives the increase, then “both he that soweth and he that reapeth [will] rejoice together” (John 4:36).

3:9 labourers together with God. Both the Father and the Son have been working together ever since the fall of man on their great work of reconciling man to God (note John 5:17), and we have the great privilege of sharing in this “ministry of reconciliation” (II Corinthians 5:18). Our faithfulness in this “labour in the Lord” (Romans 16:12) will be evaluated when Christ comes again “to give every man according as his work shall be” (Revelation 22:12).

3:10 masterbuilder. “Masterbuilder” is the Greek architekton, meaning essentially “structural engineer.”