<p>3:19- see on Jn. 3:3.</p><p><i>So we see that they were not able to enter in because of their unbelief</i>- See on :18. The essential problem with Israel was not their moral failure but their disbelief that really they would be saved. They did not enter in because they chose themselves not to. But once rejected, they then did attempt to enter the land, not by faith but in their own strength; and they were not able to enter (Num. 14:40-45). This again was a pertinent challenge to the Hebrew Christians returning to Judaism. Entry to the Kingdom of God can only be by faith that we shall do so; any attempt to enter in our own strength will leave us realizing all too late that we &quot;were not able to enter in&quot; because we lacked faith, even if we had belated desire and human effort. The <i>dunamis</i> ('ability') to enter the Kingdom is the <i>dunamis</i> of the Spirit gift, which is predicated upon faith alone (Eph. 3:16-20); the idea is parallel with not being able to see the Kingdom cp. Moses seeing the promised land unless we receive the birth of the Spirit (Jn. 3:3,5). &quot;Cannot enter into&quot; in Jn. 3:5 translates the very Greek phrase found here &quot;not able to enter in&quot;.</p>