<p>17:21- see on Jn. 13:35.</p><p><i>That they may all be one, even as You, Father, are in me and I in You, that they may also be one in us; that the world may believe You did send me</i>- As noted on 14:2,3 and throughout the Comforter discourse, the Lord intended that the relationship He had with the Father (&quot;where I am&quot;) would be experienced by all those who received His Spirit. The unity in view here is expressed in a slightly ambiguous way because it is two-fold. Unity between the believer and the Son and Father; and thereby unity between each other, between preacher and convert, and convert and convert. This would be achieved through being together &quot;in us&quot;, as the Son and Father mutually indwelt each other. The source of this indwelling was the Spirit; 1 Jn. 4:13 alludes here: &quot;Hereby we know that we abide in him and He in us, because He has given us of his Spirit&quot;. Those who resist the idea of the indwelling Spirit are invariably not at one with their brethren, and thereby not at one with the Father and Son. For it is through the mutual indwelling of the Spirit that He is in us and we in Him; and thereby we are all one with each other.</p><p>The laying down of the Shepherd's life was so that the flock might be one, in one fold (Jn. 10:15,16). The offering of the blood of Christ was <i>so that</i> He might &quot;make in himself... one new man&quot; (Eph. 2:15). Thus the theme of unity dominated the Lord's mind as He prepared for His death. &quot;For their sakes I sanctify myself in the death of the cross... that they all may be one&quot; (Jn. 17:19,21). The glory of God would be the source of this unity in Christ (Jn. 17:22); and that Name and glory were declared supremely on the cross (Jn. 12:28; 17:26). The grace, mercy, judgment of sin, the goodness and severity of God (Ex. 34:5-7)... all these things, as demonstrated by the cross, bind men together. And thus in practice, both a too strict and also too loose attitude to doctrine and practice, an unbalanced understanding of the glory of God, will never bring unity.</p><p>This unique unity, the &quot;unity of the Spirit&quot;, brought about by the indwelling of the Spirit (see on Eph. 4:3), will be so compelling that the world, initially the Jewish world, would believe that the Father sent the Son. It would be apparent that this unity had been created by Jesus of Nazareth, who therefore was no ordinary man, but the One supremely sent by the Father. In this thought we see continued the many allusions in this section to the great commission. The sanctification of the Son, the indwelling of the Spirit, unity between us and with the Father... all this was to be harnessed in the work of winning others for His cause.</p><p>We naturally ask why, therefore, the world, both our world and the Jewish world of John's time, have not all believed. It could be that they do not believe simply because as with the witness of the Lord, they for the most part choose to disbelieve it and reject it, lest their lives be too disturbed. But it could be that the dysfunction of the church, which is characterized by its disunity rather than unity, has meant that the potential conversion of the world to Christ has not happened.</p>